MacKenzie married Jacqueline Holland in 1968 in Camberwell. They had a daughter (born 1969) and two sons (born 1972 and 1974). His elder son and his daughter worked at Talkradio. In the late 1990s, MacKenzie was featured in The Mail on Sunday, holidaying in what the paper described as a “love nest” in Barbados with News International secretary Joanna Duckworth. MacKenzie and his wife divorced in 2006, on the grounds of his adultery. On 25 July 2008, he married Sarah McLean in Sunningdale, Berkshire, and they divorced in 2017.

In 1978, The Sun had finally overtaken the Daily Mirror in circulation becoming the newspaper with the highest sales in the UK. It was MacKenzie though who cemented the paper’s image as a right-wing tabloid, not only increasing its profile, but also making it known for its attacks on left-wing political figures and movements and its sensationalist front-page celebrity exposés. These often proved to be misleading or false, with many controversies in this area occurring during MacKenzie editorship. Commentators including The Guardian contributor Roy Greenslade and journalist John Pilger have commented on the alleged ‘Murdoch effect’. MacKenzie himself stated that he feels that his own spell as editor of The Sun had a “positively downhill impact on journalism”.

After moving back to the United Kingdom and a period as night editor of the Daily Express, Murdoch appointed him The Sun editor in 1981. Conflict between the two groups meant that MacKenzie performed both jobs for a time.

Although the coverage of the 1992 election remains the best remembered, there were many other vitriolic personal attacks on Labour leaders by MacKenzie’s Sun during elections, such as in 1983 campaign, when MacKenzie ran a front page featuring an unflattering photograph of Michael Foot, then nearly 70 years old, alongside the headline “Do You Really Want This Old Fool To Run Britain?”.

In January 1987, MacKenzie published a totally unfounded front-page story alleging that pop singer Elton John had had sex with underage rentboys. Shortly afterwards, MacKenzie published further entirely false allegations that the singer had had the voiceboxes of his guard dogs removed because their barking kept him awake at night. MacKenzie confirmed their inaccuracy shortly after publication by sending a reporter to the singer’s house, who quickly discovered that all of his guard dogs were quite capable of barking.

In April 1989, the single biggest controversy during MacKenzie’s period as editor occurred, later described in a Sun editorial in 2004 as “the most terrible mistake in our history”, during the aftermath of the Hillsborough disaster, a deadly crush which occurred during an FA Cup semi-final at Hillsborough football stadium in Sheffield claiming the lives of 96 Liverpool fans.

On the day of the 1992 election MacKenzie used the front-page headline “If Kinnock Wins Today, Will The Last Person To Leave Britain Please Turn Out The Lights”, accompanied by a picture of Kinnock’s head superimposed over a lightbulb. While the paper initially supported the government of John Major, because it appeared that Major himself shared the ideological hostility of Thatcher towards European integration, this soon changed. Following the UK’s forced exit from the European Exchange Rate Mechanism on Black Wednesday in September 1992, according to MacKenzie, Major telephoned him to ask about how the paper would report the story. While Major has denied the conversation ever took place, MacKenzie has claimed his response was: “Prime Minister, I have on my desk in front of me a very large bucket of shit which I am just about to pour all over you.”

In 1993 he told a House of Commons National Heritage Select Committee that

In January 1994, MacKenzie moved to BSkyB, another of Murdoch’s News Corporation assets, but left within a few months.

In 1995, MacKenzie joined Mirror Group Newspapers and was appointed joint boss of its fledgling L!VE TV British cable television channel. The station had previously been headed by Janet Street-Porter, who had set out to establish L!VE TV as an alternative, youth-orientated station. She clashed with MacKenzie over programme content and soon left, leaving him in sole charge.

In 1996, MacKenzie again discussed the matter on Radio 4 but this time said: “The Sun did not accuse anybody of anything. We were the vehicle for others”.

The station had a budget of only £2,000 an hour and attracted a very small audience, with an average of 200,000 viewers, but it was well-known because of the controversy and criticism surrounding its programming, which led to the station being labelled “Tabloid TV” and even “Sun TV” (in reference to the newspaper, some critics accusing MacKenzie of doing nothing more than creating a television version of his old newspaper). MacKenzie has been accused of taking a “shamelessly tacky approach”. He eventually left the station in 1997. He later said on LIVE TV:

In November 1998, MacKenzie headed a consortium, TalkCo Holdings, which purchased Talk Radio from CLT for £24.7 million. One of the financial backers was News International, News Corporation’s UK subsidiary. In 1999 TalkCo was renamed The Wireless Group and in January 2000 Talk Radio was rebranded as TalkSport. The Wireless Group acquired The Radio Partnership in 1999, gaining control of its nine local commercial stations. In May 2005, it was announced that the Northern Irish media company, UTV plc, had made an agreed offer to buy the company, subject to shareholder and regulatory approval. In June 2005, the takeover proceeded, with MacKenzie being replaced by UTV executive Scott Taunton. The station lost listeners during MacKenzie’s tenure.

MacKenzie’s commitment to Conservative, Thatcherite politics has led him to argue that Margaret Thatcher is the UK’s greatest post-war prime minister. In 2003, he presented a documentary, Kelvin Saves the Tories, in which he proposed a low-tax, anti-BBC and cautiously pro-capital punishment manifesto for the party. However, in February 2008, in a Sun newspaper article, MacKenzie claimed that he is now against the return of the death penalty.

MacKenzie was born in Thanet, Kent, to Ian and Mary MacKenzie, both journalists working for The South London Observer. When the South London Press took over their paper, Mary became press chief for the Conservative leader of the Greater London Council, Horace Cutler. Kelvin’s father died in April 2004 at the age of 84. Educated at Alleyn’s School in Dulwich, MacKenzie left school with one O-level in English literature. He joined the South East London Mercury at 17, and worked on local and then national newspapers, including the Daily Express, for the next ten years.

In September 2005, MacKenzie took over Highbury House Communications, a magazine publishing company based in Bournemouth and Orpington. HHC held a number of titles mainly in the leisure and computer games market with a ‘ladette’ title sitting uncomfortably in its portfolio. HHC was already suffering from massive debts when MacKenzie took the reins and despite efforts on his part to broker a life-line to save the ailing company, he had inherited a poisoned legacy. This venture also failed; Highbury closed in December 2005.

Despite the aforementioned criticism of the corporation, in March 2006, MacKenzie joined BBC Radio Five Live as a presenter. He made his debut on the station over the summer, presenting a series of programmes telling the story of various scandals which have occurred at FIFA World Cup tournaments over the years. He then presented a retrospective look at the year gone by on Christmas Day.

In May 2006, MacKenzie returned to The Sun, this time as a columnist, where he was accused using one of his columns to launch an attack on the people of Scotland (see below). On the subject of the columns themselves, he has said “I want to get the Lonsdale Belt for vile and be personally rude to as many people as possible.” In June 2011, it was announced that MacKenzie would leave The Sun to write a column for the Daily Mail. It emerged in December 2016, during a civil case, that he had left The Sun because Rebekah Brooks, then head of News International, and Dominic Mohan, then editor of The Sun, had not told him of the extent of the company’s phone hacking scandal. MacKenzie was also concerned about their employment of Jeremy Clarkson whose privacy injunction against his ex-wife was then in force. However he left the Mail in July 2012 after writing for the title for one year, citing an “increased commercial workload”. Subsequently, The Guardian reported that MacKenzie’s departure was due to disagreements regarding the editing of his column.

During an after-dinner speech to Newcastle-based law firm Mincoffs Solicitors on 30 November 2006, MacKenzie is reported to have said of his coverage of the Hillsborough disaster:

In July 2006, MacKenzie wrote a column for The Sun newspaper referring to Scots as “Tartan Tosspots” and apparently rejoicing in the fact that Scotland has a lower life expectancy than the rest of the United Kingdom. MacKenzie’s column provoked a storm of protest, and was heavily condemned by numerous commentators including Scottish MPs and MSPs.

The sources for these allegations were stated to be anonymous high-ranking police officers from Sheffield police and Irvine Patnick, then Conservative MP for Sheffield Hallam, who was not even present at the match. In 2007, on BBC television’s Question Time, MacKenzie additionally claimed that one of his sources was a regional news agency. The article was accompanied by graphic photographs showing Liverpool fans, including young children, choking and suffocating as they were being crushed against the perimeter fences surrounding the terraces – this was widely condemned as inappropriate.

MacKenzie then spent a year as chairman of one of the UK’s largest marketing and communications groups, Media Square plc. This was unsuccessful and MacKenzie left in March 2007.

MacKenzie was an early investor in online video company Base79, established by his son Ashley MacKenzie in 2007. They sold the firm in 2014.

On 6 January 2007, a protest took place at Anfield Stadium, the home of Liverpool F.C., during the FA Cup Third Round match against Arsenal F.C.. The protest was organised by fan group Reclaim The Kop, with the support of Liverpool F.C., and was directed towards MacKenzie personally and his continuing allegations about Hillsborough, and also towards the BBC (which was present at the stadium, broadcasting the game live on television) for employing MacKenzie as a radio presenter and paying him with television licence payers’ (and therefore public) money. Almost 12,000 people in the Kop stand held up a mosaic which spelled out the words ‘The Truth’ whilst Liverpool supporters chanted “Justice for the 96” for six minutes, signifying the length of time that the Hillsborough game played on for before being abandoned. MacKenzie did not publicly respond to the protest.

On 11 January 2007, MacKenzie appeared on BBC television’s Question Time programme, broadcast from a venue in Kent. Towards the end of the programme, MacKenzie was asked by presenter David Dimbleby about The Sun’s claims about the Hillsborough disaster. MacKenzie said that he stood by his allegation that ticketless fans were the cause of the disaster but that he does not know whether the other allegations about theft from the dead and fans urinating over victims and policemen were true. Clare Short MP suggested MacKenzie should apologise to the bereaved families and survivors who say that his claims cause them distress and hurt but he refused, claiming that it would make no difference anyway due to the bad blood between himself and Liverpool F.C. MacKenzie suggested that those who feel angry at him should instead direct their anger towards “someone who caused the disaster”. MacKenzie was heckled by some members of the audience while Short was applauded when she repeated her suggestion that he should retract his claims and apologise, but MacKenzie remained adamant that he had nothing to apologise for.

In February 2007, Independent journalist Matthew Norman claimed that MacKenzie was considering issuing a public apology for his coverage of the Hillsborough disaster, although at the time he was “still unsure” as to whether to do so. His former colleague at The Sun, Roy Greenslade has suggested that the real reason why MacKenzie may be so hesitant to apologise and admit the inaccuracy of the coverage may be his “anti-Scouse” bias, which Greenslade suspects makes it difficult for MacKenzie to “bring himself to say sorry to the city’s people”.

In 2007 MacKenzie made a series of attacks on the people of Scotland, although he is of Scottish descent – his grandfather was from Stirling.

On 11 October 2007, MacKenzie appeared on the BBC’s Question Time TV programme and launched another attack on Scotland. During a debate about tax, MacKenzie claimed that:

In May 2008, MacKenzie stood for election as a local councillor in Elmbridge. He lost the election, gaining 227 votes whereas the Conservative seat holder Glenn Dearlove won 679.

In 2011 MacKenzie launched the online TV channel Sports Tonight, describing the channel as “Sky Sports News meets TalkSport”. The channel received investment from former Conservative Party treasurer Lord Ashcroft, who took a minority stake.

On 12 September 2012, following the publication of the official report into the disaster using previously withheld government papers which has exonerated the Liverpool fans present at the match, MacKenzie issued the following statement:

On 13 January 2012, MacKenzie once again appeared on the BBC’s Question Time television programme and remarked on the move for Scottish independence:

MacKenzie joined The Daily Telegraph as an online columnist in 2013, but he was dropped by the newspaper after one column, with Roy Greenslade reporting in The Guardian that he was let go because of upset among staff on the Telegraph sports desk at his role in reporting on the Hillsborough disaster, in particular from football columnist and ex-Liverpool player Alan Hansen, who played at Hillsborough. In April 2013, The Guardian reported that the Daily Mail was being sued for libel for £200,000 over a column by MacKenzie. The claim was brought by an NHS doctor, Antonio Serrano, whom MacKenzie had criticised in the paper.

In October 2014, MacKenzie was a contestant on gameshow Pointless Celebrities. Angered viewers complained to host Richard Osman, who said that if he had known in advance, he would not have let him appear.

In December 2014 The Sun announced that MacKenzie would make a second return to the newspaper as a columnist.

Despite apologising on a number of platforms, in 2016, MacKenzie made a joke in The Sun newspaper that if it was true that George Osborne (the then Chancellor of the Exchequer) was putting gongs up for sale, he should be made Lord MacKenzie of Anfield (Liverpool FC’s home stadium).

In July 2016, after the Nice truck attack, MacKenzie wrote an article for The Sun in which he queried whether it was appropriate for Channel 4 News presenter Fatima Manji to read the news wearing a hijab. Manji accused MacKenzie of attempting to “intimidate Muslims out of public life” and attempting to smear 1.6 billion Muslims in suggesting they are inherently violent. She said, “He has attempted to smear half of them further by suggesting they are helpless slaves. And he has attempted to smear me by suggesting I would sympathise with a terrorist”.

The Independent Press Standards Organisation (IPSO) received 17 complaints about Manji wearing the hijab, an objection which was rejected. Eventually, the IPSO received 1,700 complaints about MacKenzie’s article. The IPSO ruled in October 2016 that MacKenzie was “entitled” to make his comments, and a “prejudicial or pejorative reference” to Manji’s religion was not present in the article. Manji said the ruling meant it was now “open season on minorities, and Muslims in particular”.

A day before the 28th anniversary of the Hillsborough disaster in April 2017, MacKenzie’s column in The Sun mentioned the Everton footballer Ross Barkley appearing to imply Barkley deserved to be beaten up in a nightclub incident earlier in the week. Comparing the player to a “gorilla at the zoo”, MacKenzie was accused of racism (Barkley is of part-Nigerian descent). The column was removed from the newspaper’s website on the afternoon of its day of publication. Later in the day, a spokesman for the newspaper apologised “for the offence caused” and said the columnist “has been suspended from the paper with immediate effect. The views expressed by Kelvin Mackenzie about the people of Liverpool were wrong, unfunny and are not the view of the paper”. A month after the column appeared, it was announced that MacKenzie’s “contract with News Group Newspapers”, the Sun’s publishers, “has been terminated by mutual consent”.

In response to MacKenzie’s article, on the day of its publication Everton FC banned The Sun and its reporters “from all areas of its operation” following Liverpool FC who had made such a decision about The Sun in February 2017.