Kennedy was born in Camden Street, Balaclava to Cyril William Kennedy and Mary Austen Kennedy (née Scott). Kennedy’s mother, who was 18 years old at the time of his birth, was employed at a local picture theatre. His father worked variously as an engineer and handyman, mowed lawns and washed cars. In 1939 he joined the RAAF as an air gunner. Kennedy’s first home was a “small, crowded duplex” at 32 Nelson Street, Balaclava. A 20 cm diameter plaque was placed on the property by the City of Port Phillip, coincidentally in the week of Kennedy’s death.

During a school break in 1949, Kennedy worked at his uncle’s hairdressing shop at 475 Collins Street, where he met clients who worked in the same building for the Radio Australia shortwave service of the Australian Broadcasting Commission (ABC). He accepted a job as a news runner from Collins Street to the ABC studios in Lonsdale Street. Shortly after he joined radio station 3UZ, working in the station’s record library.

By May 1957, Kennedy was appearing on television, but also presented a 3AK morning radio program with Bert Newton in 1961–1962, which later originated from a studio built at Kennedy’s home in Olivers Hill, Frankston.

Kennedy’s first television appearance was in March 1957, representing 3UZ on a GTV-9 Red Cross telethon. Viewing his performance on the monitors, GTV-9’s general manager Colin Bednall and producer Norman Spencer “… turned to one another without exchanging a word and shook hands.”

Bednall and Spencer defied both the GTV-9 boardroom and the first sponsor (Philips) by choosing Kennedy, who began on a salary of £30 for five one-hour evening shows per week to be called In Melbourne Tonight (or IMT) which began on 6 May 1957. Thus the 23-year-old Kennedy began a career of which he later said that he was “terrified for forty years”. The show’s theme song, “Gee, But You’re Swell”, was written by Abel Baer and Thomas Tobias in 1936.

By July 1959 the program was still popular in Melbourne. Recurring comedy players Joff Ellen and Rosie Sturgess became regulars. Singer Toni Lamond joined the cast. Attempts were made at this time to launch Kennedy as a national personality. Special Friday night editions of IMT were produced under the title of The Graham Kennedy Show and recorded on videotape which had just come into use. After being transmitted live in Melbourne taped copies of the show would be shipped to Adelaide, Brisbane and Sydney for transmission there on subsequent evenings. Producer Spencer observed there was critical and popular resistance to Kennedy in Sydney. Queensland too had shown suspicion to imports from down south trumpeted to Queenslanders as the best in Australia while Queensland itself had apparently been left out of this judgement.

The Graham Kennedy Show began in February 1960 but was not popular in Sydney. The program was judged stilted compared to IMT itself; Kennedy seemed much more subdued than usual, was tense, and the comedy was not working. Critics in Sydney and Queensland disliked key components of the show. Judged as a flop, The Graham Kennedy Show in Sydney was dropped by ATN7 after 13 weeks. The program however was immediately picked up by TCN9 – its general manager Ken G. Hall saw potential in the program. After continued bad reviews its popularity increased in Sydney. By July 1960 it had reached its twenty-fifth episode and had the highest ratings in Australia.

Later in 1960 Kennedy faced opposition when Sir Frank Packer bought GTV-9. Unlike the previous owner, Packer interfered directly with the station’s activities. GTV-9 executive Colin Bednall reported that Packer hated Kennedy and forcefully articulated his desire to have him removed from the IMT.

Kennedy coined the name Logie Award in 1960, after the inventor of television, John Logie Baird.

Packer’s arrival prompted the departure of IMT producer Norman Spencer. IMT continued its run. Other regular performers on IMT were Patti Newton and Philip Brady. In 1961 Kennedy described his presentation of the program.

By March 1961 the national show had been renamed Graham Kennedy’s Channel 9 Show and was finding quiet acceptance nationally. Even at this time Kennedy admitted there were problems in the weekly national show.

In January 1962 the national Graham Kennedy’s Channel 9 Show was cancelled and replaced by The Channel 9 Show hosted by Bert Newton. Kennedy continued to fine-tune his IMT performances. Kennedy had a strong understanding of key technical elements of television and perfected his comic timing, and watched the lenses on the TV cameras, adjusting his performance depending on whether he was in a wide shot or a close up. Compilation highlight programs of IMT segments were screened in Sydney, Perth, Brisbane and Adelaide in May 1963 under the title The Best of Kennedy. The Best of Kennedy continued until December 1963. On IMT, Noel Ferrier was appointed the new Friday night host. Also in 1963 writer Mike McColl-Jones joined. Kennedy had often disliked having writers on the program, was reluctant for them to be publicly acknowledged, and often ignored all their material. In the case of McColl-Jones, Kennedy seemed to like him and his comedy material, which was apparently the key requirement by which Kennedy would use a writer’s material. McColl-Jones continued as a writer on the series for several years. Also in 1963 Ernie Carroll joined the writing team. Kennedy had apparently relaxed his attitude towards writers by this stage and seemed happy to use their material with few complaints.

In 1964 Bert Newton abruptly disappeared from the program. It was not publicly acknowledged at the time but he had suffered a nervous breakdown. After a long absence he returned to appear on the Monday, Tuesday and Wednesday evening episodes. On 14 June 1965 IMT reached its 2,000th instalment and more people watched the show per capita than any other television program in the world.

On 7 July 1965 Kennedy appeared on a then-innovative live split-screen link with Don Lane, the host of Sydney Tonight, via the recently completed co-axial cable linking Melbourne and Sydney. Starting late September 1966, IMT itself was transmitted to Sydney via the coaxial cable. This coincided with a cameo in the film They’re a Weird Mob in which Kennedy plays himself. Like the film’s protagonist, Kennedy in the film finds Sydney to be a city somewhat unwelcoming towards migrants from anywhere. By early December 1966 ratings for Kennedy’s show were strong in Sydney. There was an increase from one IMT episode a week in Sydney, to two, with a Monday night broadcast added that month.

By 1968 there was a regular roster of IMT guest hosts, including Bert Newton, Tim Evans, Bobby Limb, Don Lane, Kevin Sanders, and Michael Preston. The announcement of Kennedy’s intention to leave IMT was made in October 1969 and he left the show on the expiration of his contract 23 December 1969. His final episode features newsreader Sir Eric Pearce placing on his head a crown made by the Channel Nine prop department in the style of that worn by Henry IV, symbolising Kennedy’s reign as King of Australian television.

In 1970 he worked at 3XY; from June to December 1975 he appeared on a 3LO drivetime program with Richard Combe; from September to November 1976 was on 3DB with Denis Scanlan; in 1977 he returned to DB to cover the Silver Jubilee of Elizabeth II live from London.

After specials on 15 November 1971 and 2 March 1972, Kennedy returned to regular television with The Graham Kennedy Show on 19 September 1972. This series lasted until late 1973. In 1974, when Kennedy claimed he wanted a rest, Nine allegedly paid him not to sign with another network. It was Frank Packer who paid Kennedy $50,000 to do nothing, as he was fearful he would work for someone else. Kennedy said in 1978:

In 1973 Melbourne newspapers reported that Kennedy was engaged to 28-year-old Australian singer Lana Cantrell, who became a successful New York lawyer. Many years later, Kennedy wrote to a newspaper that a photographer, taking pictures of him and Cantrell leaving a restaurant together asked if he could “hint at a romance”. The following Sunday a poster proclaimed “Graham and Lana to wed”. His former housekeeper, Devona Fox, in the 2009 television documentary The Real Graham Kennedy, produced by Bob Phillips, one of the producers from Kennedy’s breakthrough Channel 9 program In Melbourne Tonight, is quoted as saying:

The Graham Kennedy Show resumed in March 1975, and was Kennedy’s first series in colour.

Memorable, and controversial, moments, included the “crow call” controversy where, on 3 March 1975, Kennedy imitated a crow call (“faaaaaark”) highly reminiscent of the word “fuck”. This led the Australian Broadcasting Control Board to request that Kennedy “show cause” why he should not be removed from the airwaves. Kennedy replied that he could not show cause, suggesting that the Board take action to limit his appearances, while hinting at legal action should they do so. Rather than removing him, the ABCB banned Kennedy from appearing live, forcing him to pre-record the show on videotape.

Kennedy appeared as Clive Parker in an episode of the 26-part ABC drama Power Without Glory, which began on 21 June 1976.

In 1977, Kennedy chaired a project to raise funds for improvements at Melbourne High which raised more than $100,000 in its first year.

He returned to television in 1977 for what is now Network Ten to host a comedy game show, Blankety Blanks. It dominated early evening television over two seasons, between 7 February 1977 and 15 September 1978. The show featured friends from his earlier days including Noeline Brown, Barry Creyton, Noel Ferrier, Ugly Dave Gray, Carol Raye and Stuart Wagstaff. It was only after the show became a ratings success and the network’s most profitable program that it revealed Kennedy was paid an unprecedented $1 million per season.

In 1979, “The King” became King of Moomba complete with his famous motorised desk, the second Melbourne-born recipient after Newton.

In 1980 Kennedy became a ten percent shareholder in Sydney radio station 2Day FM and from 24 May 1981 presented a computer-edited, three-hour Sunday morning program of music and comedy.

In 1982 Kennedy provided the voice-over narration for a ten-episode ABC historical documentary The Blainey View.

Kennedy appeared as the host of Channel Seven’s morning news program Eleven AM in 1983 and again – for eight weeks – in 1984.

On 13 February 1989 the show became Coast to Coast, with Nine journalist John Mangos replacing Sutcliffe, and ran until 8 December 1989.

Miller later sued Kennedy for “wrongful termination and for a 20 per cent commission on his 1989 gross earnings.” During the court case Miller “painted a picture of his client of twenty years as a late-night drunk in the habit of sending demanding faxes while under the influence.” Justice Brownie found against Miller, and ordered him to pay $75,699 and costs.

Kennedy presented the introduction segment to the Nine Network special 35 Years of Television in 1991. The segment covered the very early days of television variety, including his own In Melbourne Tonight.

In 1991 Kennedy retired to a rural property at Canyonleigh, near Bowral in the Southern Highlands of New South Wales, near his friends Tony Sattler and Noeline Brown, where his main companions were two Clydesdale horses named Dave and Sarah, and Henry, a Golden Retriever.

Kennedy’s last television appearance was in February 1994 in an interview for Ray Martin Presents Graham Kennedy’s Sixtieth. Believing that Martin had ambushed him by departing from a pre-agreed list of questions, Kennedy ensured that much of the interview was unusable for broadcast by peppering his responses with obscenities.

On 18 December 2001 his housekeeper found him unconscious and dehydrated. Sattler said “Between the diabetes and the booze, there’s not much left of him”, adding that the death of Kennedy’s dog Henry was “the final trigger”.

In 2001 Kennedy’s friend and Coast to Coast colleague, John Mangos, was reported as saying:

On 14 June 2002 Kennedy was found unconscious at the foot of the stairs at his home, suffering a broken leg and skull with suspected brain damage.

On 27 May 2005, Noeline Brown confirmed that the benefactor was Sam Chisholm.

On 25 May 2005, aged 71, Kennedy died at the Kenilworth Nursing Home, Bowral, from complications from pneumonia.

The Age newspaper, on 26 June 2005, reported John Mangos as saying that he “knew Kennedy wanted his ashes scattered at sea. And that wish was carried out.” This was confirmed in a report in The Sydney Morning Herald which stated that Kennedy’s ashes were scattered in the sea at Kiama attended by a group which included “Noeline Brown, Tony Sattler, John Mangos, Stuart Wagstaff, Kennedy’s former housekeeper Sally Baker-Beall and her husband John, and old friends Christine and Nicholas Deeprose.”

Four of Kennedy’s television shows were named in the program 50 Years 50 Shows which counted-down the top 50 Australian TV shows of all time, as decided by ratings data and the opinions of 100 television industry professionals, on the Nine Network on 25 September 2005. Kennedy’s In Melbourne Tonight topped the poll, Power Without Glory (15th), Blankety Blanks (20th) and Coast to Coast (42nd).

In his 2006 book King and I: My Life with Graham Kennedy, published by celebrity agent Anthony Zammit, broadcaster Rob Astbury stated that Kennedy and he had been lovers. Kennedy is portrayed as homosexual in the 2007 biopic The King.

A telemovie examining Kennedy’s life, titled The King, began filming in December 2006. It stars Stephen Curry as Kennedy and Stephen Hall as Bert Newton, with Garry McDonald, Shaun Micallef, Steve Bisley, Jane Allsop as Noeline Brown, Beau Brady, Leo Taylor as Sir Frank Packer and Bernard Curry as John Wesley.

In 2007, the crown (which a private collector had recognised at a junk store in Bowral NSW, and purchased for $5) was auctioned for more than $17,000 to a producer of the Seven Network’s Sunrise program.

The project, which cost $2.1 million, premiered on 20 May 2007 on TV1 (becoming the highest-rating drama to be shown on pay-TV) to heavy criticism by Kennedy’s friends. Tony Sattler and his wife, actress Noeline Brown, Kennedy’s closest friends, said they were mortified by the movie, saying that “The film was obsessed with his homosexuality. I don’t think people cared about that … He was Australia’s most famous, successful entertainer but how much do we see of that in the film? We see fuck all of it.” The Nine Network screened the film on 27 August 2007 .