Little was an usher at the Elgin Movie Theatre in Ottawa, where he would perfect his voices while standing at the back of the theatre. He started his amateur acting career at the Ottawa Little Theatre, winning his first acting award at the Eastern Ontario Drama Festival in Deep River, Ontario. At 17, he and friend and fellow impressionist Geoff Scott won a talent contest on ‘on CBOT in Ottawa, the first time he was paid for his impressionist skills, which led to an appearance on Pick the Stars, a national talent contest broadcast by CBC Television in 1956. They then appeared on The Jackie Rae Show during the 1956-57 season.

Little was born in Ottawa, Ontario, Canada, the middle of three sons. His father, Lawrence Peniston Little, was a surgeon who served as a lieutenant commander in the Royal Canadian Naval Volunteer Reserve during World War II and then worked for the Department of Veterans’ Affairs until his death in 1959. His mother, Elizabeth Maud (née Wilson), was a housewife. A third-generation Canadian, he is descended from English stock on his father’s side and Irish on his mother’s. On his mother’s side, he is descended from John Willson, who was Speaker of the 5th Parliament of Upper Canada in the 1820s. Little’s paternal great-grandfather, William Carruthers Little, was a Liberal-Conservative Member of Parliament in the Canadian House of Commons from 1867 to 1881.

In 1963, Little issued two LPs through the Canadian division of Capitol Records; the first, My Fellow Canadians which he performed with Les Lye and which concentrated on Canadian political satire and featured Little and two other actors impersonating figures well-known to a Canadian audience such as Diefenbaker, Lester Pearson and Tommy Douglas. The second album, Scrooge and the Stars, featured Little acting out Charles Dickens’ A Christmas Carol entirely on his own, playing all the roles as 22 different Hollywood stars, ranging from Jack Benny to Jack Webb. The album was released in early November but it had to be withdrawn a few weeks later due to the assassination of John F. Kennedy as Little had imitated JFK in the role of the Spirit of Christmas Present and had Kennedy say the line “Scrooge, my life upon the globe is brief; it ends tonight. In fact, it ends as fast as you can say your name.”

Little’s first performance in the US was in December 1963 at Guy Lombardo’s inn and country club in Tierra Verde, Florida.

The audition won him the job, and in January 1964 Little made his American television debut on CBS’s The Judy Garland Show, where he impressed Garland by imitating various male celebrities, including James Mason who had been Garland’s co-star in A Star Is Born. Television appearances on variety shows hosted by Ed Sullivan, Jackie Gleason, Rudy Vallee, Mike Douglas, George Burns, and Al Hirt followed over the next two years.

In 1965, Little provided the voice for the Pink Panther in two experimental cartoons, Sink Pink and Pink Ice.

Little was engaged to Canadian actress Jean Christopher in 1965 but they did not end up marrying.

In Canada, Little starred in his own show The Rich Little Show, on CBC Radio in 1966. He also made his first appearances on The Dean Martin Show and The Jimmy Dean Show during the 1965-1966 season.

In 1966 and 1967, Little appeared in ABC-TV’s Judy Carne sitcom Love on a Rooftop as the Willises’ eccentric neighbour, Stan Parker. He appeared on That Girl in 1967 as a writer who impressed Marlo Thomas’ character with his impersonations. He also made two memorable appearances as accident-prone Brother Paul Leonardi on The Flying Nun in 1968; it marked one of his few appearances as a character actor rather than an impressionist. In 1969 he appeared in an episode of Petticoat Junction as newly engaged fiance to Billie Jo in “Billie Jo and the Big Big Star”.

Little has been appearing in Las Vegas since the mid-1960s when he had dates at the Golden Nugget and would go on to play at other Vegas venues such as The Sands, where he debuted in 1969 with a two-year contract. In 1973, he performed at Caesars Palace for four weeks in 1973 as the opening act for The Osmonds. He then appeared at the Desert Inn with Juliet Prowse for a month in 1974. His appearances continued throughout the 1970s and 1980s; he headlined at the Desert Inn for eight years in the late 1970s and 1980s, at the MGM Grand with Nell Carter in 1985; at Bally’s, with Charo in 1986; the Sands in 1991 and 1992 as well as at the Golden Nugget in 1991.

Little was married to Jeanne Worden, whom he met when she was working as a secretary on The Joey Bishop Show, in 1971. The couple had a daughter together, Bria, before their divorce in 1989. Little had a brief relationship with Lalette Cottrell, of Delaware; the couple had a daughter together, Lyndsay (born 1988).

Little’s best-known continuing TV series was The Kopycats, hour-long segments of The ABC Comedy Hour, broadcast in 1972. Taped in England, these comedy-variety shows consisted entirely of celebrity impersonations, with the actors in full costume and makeup for every sketch. The cast included Little, Frank Gorshin, Marilyn Michaels, George Kirby, British comedian Joe Baker, Fred Travalena, Charlie Callas and Peter Goodwright.

Little was a frequent guest on variety and talk shows in the 1960s and 1970s and had an unofficial monthly slot on The Tonight Show Starring Johnny Carson for several years, and also guest hosted the program about a dozen times. He developed an impression of Johnny Carson, capturing The Tonight Show host’s voice and many onstage mannerisms and later played Carson in the HBO TV-movie The Late Shift. Little’s spot-on impersonation allegedly got under the thin skin of Carson and he was permanently banned from appearing on the Tonight Show without notice or reason after his August 1982 appearance. Little claims in his biography that he was banned because Carson was offended by his impression and this claim was supported by Henry Bushkin, Carson’s long-time lawyer, who stated that nobody got under Carson’s skin more than Little. However, Little had been doing the impression since the early 1970s, a decade prior to his bookings on the show coming to an end, including performing the impression to the Tonight Show’s host face when Carson was the guest of honor at The Dean Martin Celebrity Roast of Johnny Carson in 1973. In response to Little’s claims, Fred DeCordova, Carson’s producer, said they just weren’t interested in hiring him any more due to his lack of new impressions.

Little was also a semi-regular on the Emmy-winning ABC-TV variety series The Julie Andrews Hour in 1972–73. In response to his imitation of Jack Benny, the comedian sent Little an 18-carat gold money clip containing this message: “With Bob Hope doing my walk and you doing my voice, I can be a star and do nothing.” He was named “Comedy Star of the Year” by the American Guild of Variety Artists in 1974.

In 1981 Little appeared in a comedy LP called The First Family Rides Again, which was the fourth and final of the First Family comedy LPs originally created by Bob Booker and Earle Doud. Little starred along with Melanie Chartoff, Michael Richards, Shelly Black, Jenilee Harrison, Earle Doud, and Vaughn Meader, making light of U.S. President Ronald Reagan’s first few months in the White House.

Little has starred in various HBO specials including the 1978 one-man show, Rich Little’s Christmas Carol, which was produced by and originally aired on CBC Television, in which Little portrayed famous comedians in established roles (W. C. Fields as Ebenezer Scrooge, Paul Lynde as Bob Cratchit, et al). He followed this up with another HBO special in 1983, Rich Little’s Robin Hood, in which he portrayed Groucho Marx as Robin Hood, Humphrey Bogart as Prince John, John Wayne as Little John, Carol Channing as Maid Marion, Laurel & Hardy as Sheriffs of Nottingham, George Burns as Alan-a-Dale, and various other characters.

Outside of any comedic context, Little’s talent for impersonation has been used in movies when an actor’s dialogue was impaired by poor health. When David Niven proved too ill for his voice to be used in his appearances in Trail of the Pink Panther (1982) and Curse of the Pink Panther (1983), Little provided the overdub as an imitation of Niven’s voice. He performed similar duties to dub an imitation of James Cagney’s stroke-impaired voice in the 1984 TV movie Terrible Joe Moran and in the 1991 TV special Christmas at the Movies by providing an uncredited dub for actor/dancer Gene Kelly who had lost his voice.

In 1987, during the We the People 200: The Constitutional Gala television special, Little personified various historical figures including Franklin D. Roosevelt, Edward R. Murrow, John F. Kennedy, Martin Luther King Jr. and Robert F. Kennedy. Little’s performance was described as eclectic, impersonating Henry Fonda as Abraham Lincoln and doing Winston Churchill giving a rousing speech.

Little relocated to Vegas in 1990, and sold his house in Los Angeles and bought a home in Vegas in 1992, when he signed an exclusive long-term contract with the Sahara, staging a revamped version of “The Kopykats” with other impersonators. He later moved to Paris Las Vegas, where he starred in The Presidents, a play on nine Presidents of the United States from Kennedy to George W. Bush starting in 2002. In 2004, he moved to The Suncoast.

One of his best-known impressions is of U.S. President Richard Nixon (reprising in 1991 the role of Nixon as ideal sperm donor in Gina’s fantasies on the soap opera Santa Barbara). During the 1970s, Little made many television appearances portraying Nixon and once performed his impersonation in front of Nixon himself, who Little says did not realize he was imitating him at all and “wondered why I was talking to him in such a funny voice.” In 1972, he portrayed Richard Nixon with the voice and mannerisms of Oliver Hardy in Another Nice Mess.

Little was engaged to magician Melinda Saxe, but she broke off the three-year relationship in 1991, saying she had discovered that he had secretly videotaped them having sex in 1988. Saxe sued Little for defamation, invasion of privacy, and inflicting emotional distress, claiming he had secretly videotaped their sexual encounters in 1988 and had joked about their relationship on stage. Little claimed the videotaping was consensual. The lawsuit was eventually settled out of court.

He married comedian and impressionist Jeannette Markey in 1994; they divorced in 1997. He was married to Marie Marotta from 2003 until her death in 2010 of a deliberate overdose of sleeping pills after years of suffering from migraines and chronic pain. He married his fourth wife, Catherine Brown, a former reality show contestant, in a private ceremony in 2012; they divorced in October later that year.

In 1998, Little was inducted into Canada’s Walk of Fame. Little was inducted into the Casino Legends Hall of Fame in 1999 and given a star on the Las Vegas Walk of Stars in 2005.

In 1998, a Golden Palm Star on the Palm Springs, California, Walk of Stars was dedicated to him.

In 2010, Little became a naturalized American citizen.

Since 2015, Little has a regular performer at the Laugh Factory in the Tropicana hotel in Las Vegas. His one-hour show, Rich Little Live!, is a career retrospective including video highlights from his TV career and is performed five nights a week. Throughout the show, he displays many of the charcoal sketches he has drawn of the celebrities he has impersonated.

In 2017, Little released his memoir, Little By Little: People I Have Known And Been.

In 2020, he developed a one-man show around the late president, titled “Trial on the Potomac- The Impeachment of Richard Nixon”. based on the book The Real Watergate Scandal, Collusion, Conspiracy, and the Plot That Brought Nixon Down by Geoff Shepard, which alleged a conspiracy to remove Nixon from office.