Lomu was born in Greenlane Hospital in Auckland on 12 May 1975 to Tongan parents. He spent some of his early childhood in Tonga with his aunt Longo and uncle Mosese, and lived in the Auckland suburb of Mangere. There he was exposed to gang violence losing an uncle and a cousin to attacks. This led his mother to send him to Wesley College in Auckland. There, he excelled in athletics, in particular, the 100 metres, shot put, javelin, high jump, hurdles and relay. In his final year, he ran the 100 mts in 11.2 seconds. By 1993, during his last year at Wesley, he started playing rugby more seriously, while still combining it with athletics.

Lomu started his rugby union career in the forwards, mostly as an openside flanker (no.7), sometimes to the blindside (no.6), before switching to the left wing in what he described as the “best move he could have made”. He represented New Zealand in the national under-19 side in 1993, as well as the under-21 side the following year. He first came to international attention at the 1994 Hong Kong Sevens tournament as part of a team including Rush.

At the age of 19 years and 45 days, Lomu became the youngest All Black test player as he debuted on the wing against France in 1994, breaking a record that had been held by Edgar Wrigley since 1905. The match was played at Lancaster Park in Christchurch, and the All Blacks lost 22–8. The second match was played at Eden Park in Auckland with France winning again, 23–20. Lomu marked Emile N’tamack and admits that his inexperience led to him being exposed by the French team.

Before 1995, wingers were generally fast and good on their feet. Lomu was the first truly massive wing, a trend that has now become standard in many teams. Lomu has been described as the first true global superstar of rugby union and as having a huge impact on the game, with comparisons being drawn with Muhammad Ali, Don Bradman and Tiger Woods. At one time he was considered ‘rugby union’s biggest drawcard’, as his appearance at a match would increase attendance.

Following his displays at the 1995 Rugby World Cup, in December 1995 Lomu received the BBC Overseas Sports Personality of the Year, an award given to a non-British sportsperson considered to have made the most substantial contribution to a sport each year who has also captured the imagination of the British public.

Lomu lent his name to various video games including Jonah Lomu Rugby and Rugby Challenge. He is portrayed by Isaac Fe’aunati in Invictus, a film chronicling Nelson Mandela’s journey with the South African rugby team in the 1995 World Cup.

Following the World Cup New Zealand played Australia home and away for the Bledisloe Cup with Lomu scoring tries in both matches. Lomu’s scoring for New Zealand continued later that year when he scored two tries in the All Blacks victory over Italy in Bologna. Lomu played in a losing effort against France in Toulouse, where New Zealand failed to score any tries. He scored a try in the second test in Paris, helping his team to victory. Lomu played for the All Blacks in matches against the touring Samoa and Scotland teams in June 1996, scoring in one of the Scottish matches.

In 1996, Lomu married South African Tanya Rutter and they lived together in New Zealand for four years before divorcing, of which his family never approved. He married his second wife Fiona in a secret ceremony on Waiheke Island in August 2003, holding a party on the island a week later. In 2008, Lomu and Fiona divorced after he had an affair with Nadene Quirk. Lomu and Nadene later married in 2011 and at the time of his death he was living with Nadene and their children, Brayley and Dhyreille.

In 1996, McDonald’s New Zealand named a burger after Lomu, temporarily rebranding the McFeast burger line (called “Mega Feast” in New Zealand) as the “Jonah Burger”.

At the end of 1996, he was diagnosed with a rare and serious kidney disorder, which saw him take time off from the sport. As a result, he did not play in the 1997 Tri Nations Series, but he was included in the All Blacks tour of the northern hemisphere at the end of the year. Lomu played in the two warm up matches, scoring tries against Wales ‘A’ and Emerging England. He played the first test against England at Old Trafford, as well as the test against Wales at Wembley Stadium, and the second match against England—he did not score in any of the three games.

At the 1998 Commonwealth Games in Kuala Lumpur, he won a gold medal representing New Zealand in the Sevens Rugby event. The English rugby team came to New Zealand the following year for a two test series. Lomu played in both of the matches, scoring in the first, which was a 64–22 win in Dunedin, but not in the second test won 40–10 by the All Blacks.

Lomu’s 1999 international season kicked off with a warm-up match against New Zealand A, which was followed by a game against Samoa in which Lomu scored one of the All Blacks’ nine tries. He came on as a replacement in every game of the 1999 Tri Nations Series with Christian Cullen and Tana Umaga preferred as starters on the wings. New Zealand were crowned Tri Nations champions despite losing the last game against Australia.

During the 1999 off season, Lomu transferred to Wellington, signing up with second division club Wainuiomata RFC. Lomu played his debut match against Northern United scoring twice and attracting a bumper crowd and followed that up with a further appearance in 2001. Lomu wore the green and black club socks when he played for the Barbarian F.C. in 2000.

Lomu was the director and a shareholder in Global 11 Travel, which was liquidated in 1999. At the time of his death, he owed money on property investments, as well as loans taken out to buy personal vehicles. His family were living in a rented $2.2 million (NZD) Auckland home. Lomu had sold some of his properties a decade prior, including his Maupuia mansion bought in 2000, which sold three years later for a reported $1.4 million (NZD).

Lomu started 2000 with big victories over Tonga and Scotland. The opening match of the 2000 Tri Nations Series was played in front of a record crowd of 109,874 and has been labelled the “match of the century’.’ New Zealand scored three tries in the first five minutes to lead by 21 points, before Australia came back, leveling the scores before half time. With minutes remaining, the Wallabies led 35 to 34; until Lomu “brushed past a desperate Stephen Larkham to tip-toe down the line and score the winning try”. The match was followed by a victory over South Africa, and then a re-match with Australia, which Australia won 24 to 23. New Zealand lost the final game to South Africa finishing second in the table, behind Australia. Lomu played in one other test that year; against France at Stade de France in November, which the All Blacks won 39 to 26.

After the game, England captain Will Carling said: “He is a freak and the sooner he goes away the better”. His first score was voted the try of the tournament. In 2002 the UK public voted Lomu’s performance no. 19 in the list of the 100 Greatest Sporting Moments. New Zealand played the World Cup final at Ellis Park against South Africa. Neither side scored a try, with South Africa coming out on top 15–12 after kicking a drop-goal in extra time.

He returned to the wing for a game against England in November 2002. Lomu ended up scoring two tries, though it was not enough to secure a New Zealand victory, with England winning 31–28. The subsequent match against France resulted in a draw, the first between the two nations in 96 years. The last match of the end of season tour was against Wales, which the All Blacks won 43–17. These were the last international matches that Lomu would play for New Zealand as his illness worsened and he needed a kidney transplant.

At the end of 1995, Lomu was diagnosed with nephrotic syndrome, a serious kidney disorder. His rugby union career went on hold whilst the disorder was treated. In May 2003, the NZRFU announced that Lomu had been put on dialysis three times a week due to deterioration in his kidney function. Side effects of Lomu’s dialysis treatment led to severe nerve damage in his feet and legs; his doctors warned him that he faced life in a wheelchair if a kidney transplant was not performed soon. At the end of July 2004 it was reported that Lomu had indeed undergone a kidney transplant on Tuesday, 28 July, in Auckland, New Zealand. The kidney was donated by Wellington radio presenter Grant Kereama.

Lomu returned to professional rugby in 2005. He first needed special clearance from the World Anti-Doping Agency, as one of the anti-rejection drugs he was required to take is on the WADA list of banned substances. On 8 April 2005, he signed a two-year contract to play for the New Zealand first division provincial team North Harbour in the NPC. He ended up missing the first season when he injured his shoulder scoring a try in a preseason testimonial match against Martin Johnson’s invitational XV. Instead he worked in a coaching capacity. North Harbour gave him permission to play overseas at the Cardiff Blues over the off season.

Lomu made his first appearance in a competitive match since his transplant on 10 December 2005, with a 60-minute effort in Cardiff’s away Heineken Cup fixture against Italian club Calvisano. Lomu scored his first try for Cardiff on 27 December, with a man-of-the-match performance during a 41–23 win against the Newport Gwent Dragons. He spent the early part of 2006 sidelined while he concentrated on gaining speed and strength not playing again until April. He broke his ankle near the end of his first game back, ending his season with Cardiff. During his time in Wales, he played 10 games and scored one try.

Lomu retired from professional rugby in 2007, but still took part in some charity matches. He was going to play in the Help For Heroes charity match at Twickenham in 2008, but had to withdraw after injuring his ankle in training. Later that year Lomu played in a charity match at Aberavon RFC’s Talbot Athletic grounds to raise money for a local children’s charity. The match was covered by the BBC rugby show Scrum V.

On 9 April 2007, Lomu appeared on New Zealand’s version of This Is Your Life, in which he was reunited with long time friend Grant Kereama, who had donated a kidney to Lomu when he underwent a kidney transplant in July 2004. He was a subject of the British version of This Is Your Life in 2002 when he was surprised by Michael Aspel while touring with the All Blacks in Edinburgh.

Lomu was inducted into the International Rugby Hall of Fame on 9 October 2007, and the IRB Hall of Fame on 24 October 2011. He was appointed as a Member of the New Zealand Order of Merit, for services to rugby, in the 2007 Queen’s Birthday Honours.

In September 2009, Lomu took part in an amateur bodybuilding contest, finishing second in two categories, including the men’s open over-90 kg, and the mixed pairs. He joined French Fédérale 1 team Marseille Vitrolles in November, making his debut in a 64–13 victory over against Montmelian. Lomu started the match at centre then moved to number 8, the position he played as a youngster in New Zealand.

Lomu was a member of the Champions for Peace club, a group of 54 famous elite athletes committed to serving peace in the world through sport, created by Peace and Sport, a Monaco-based international organisation. In 2012, Lomu and Nadene became members of The Church of Jesus Christ of Latter-day Saints.

Lomu scored tries against every major test playing nation in World Rugby except South Africa (12 matches) and Wales (3 matches). In his career, Lomu scored eight tries against England—more than any other All Black. Lomu set a record of 15 tries in World Cup tournaments, which was equalled by South African Bryan Habana in 2015.

On the morning of 18 November 2015, Lomu died unexpectedly in Auckland from a heart attack linked to his kidney disease. The previous night he had returned from the United Kingdom with his family after a short holiday stay in Dubai. Lomu had been receiving dialysis treatments during his visit to the UK where he was involved in heavy promotional work during the 2015 Rugby World Cup. His first public service was held in his home church in Mangere, Auckland, with Lomu’s family members in attendance. Two public services were held at Vodafone Events Centre in Manukau on 28 November 2015, and at Eden Park on 30 November 2015, a day before a private service.

In March 2018, Jonah Lomu Drive, in the Paerata Rise development north of Pukekohe, was named in his honour.