Walter John Buchanan was born in 1891 in Helensburgh, the son of Walter John Buchanan Sr (auctioneer) and Patricia, née McWatt. Jack attended Larchfield School, Helensburgh, and was a classmate of John Logie Baird for a short time before his father died when he was 12. The family moved to Glasgow where Jack was sent to Glasgow Academy and spent some time at Glasgow University before leaving to become an auctioneer. His first love was amateur dramatic and music hall but after failing to make it as an auctioneer he moved to London in 1912 and worked as an understudy and chorus boy before becoming a music hall comedian, appearing as Chump Buchanan. At first it was a struggle but eventually he was cast in the comic opera The Grass Widow at the Apollo Theatre. After he was declared unfit for military service in World War I. he threw himself into his West End theatre work, attracting favourable notices as a character and dancer. Between 1915–17 he toured in successful play Tonight's the Night.
Jack Buchanan made his film debut in the silent cinema, in the British silent crime film Auld Lang Syne (Sidney Morgan, 1917), starring Violet Graham. Soon he played the lead role in such silent British films as the comedy The Audacious Mr. Squire (Edwin Greenwood, 1923), Bulldog Drummond’s Third Round (1925) with Buchanan as Bulldog Drummond, and the drama Confetti (Graham Cutts, 1927) with Annette Benson. Most of the movies were second-rate, with Jack hopelessly miscast in them. On stage Jack took over from Jack Hulbert in André Charlot’s revue Bubbly, followed by another Charlot show, A To Z, in 1921. It was here Buchanan’s talent was finally recognised and he sang one of his all-time hits, ‘And Her Mother Came Too’, with Ivor Novello’s music and a lyric by Dion Titheradge. In the cast were Beatrice Lillie and a young Gertrude Lawrence. The show transferred successfully to Broadway in 1924.
In 1926 in another Charlot revue, he duetted with Gertrude Lawrence on ‘A Cup Of Coffee, A Sandwich, And You’ and the song became a massive hit in America.
Back in London, Jack teamed up with Elsie Randolph and together they appeared in dancing musicals such as Sunny, That’s A Good Girl, Mr. Whittington, This’ll Make You Whistle. For the next decade Jack flirted and joked his way through musical shows with his tall figure, elegant gestures, and the friendly drawling voice, generally having mass appeal with theatre audiences eager to forget the trials and tribulations of their daily lives. He made his debut in "talkies" in America in leading roles opposite Irene Bordoni in Paris (Clarence G. Badger, 1929), and Jeanette MacDonald in Monte Carlo (1930). His casting was not especially successful and Jack returned to England to continue his film career there.
During the 1930s, he appeared in many British films including: A man of Mayfair (Louis Mercanton, 1931) with Joan Barry and Warwick Ward; Goodnight Vienna/Magic Night (Herbert Wilcox, 1932) opposite Anna Neagle; That’s a good girl (1933); Yes, Mr. Brown (Herbert Wilcox, 1933); Brewster's Millions (Thornton Freeland, 1935) with Lily Damita ; Come Out of the Pantry (Jack Raymond, 1935) and When Knights Were Bold (1936) with Fay Wray; and Smash and Grab (Tim Whelan, 1937). In partnership with J. Arthur Rank and Charles Woolf, in 1937 he formed Jack Buchanan Productions which owned Riverside Studios in Hammersmith. He produced and directed The Sky's the Limit (1938). British film exhibitors voted him among the top ten British stars at the box office (1936, 1937 and 1938), via an annual poll in the Motion Picture Herald.
In 1938 whilst starring in the London stage musical This'll Make You Whistle, he was concurrently filming a film version and it was released while the stage version was still running. More British films of that period were Break the News (René Clair, 1938) with Maurice Chevalier, The Gang's All Here (Thornton Freeland, 1939) with Googie Withers, and The Middle Watch (Thomas Bentley, 1940) with Greta Gynt.
During the Second World War, he frequently produced his own shows, many of which were premiered in the Alhambra Theatre, Glasgow. He starred in his own musical production "It's Time to Dance", with Fred Emney, at the Lyric Theatre; and later revived Battling Butler at the New Oxford Theatre. Jack had an eye for business and was responsible, with partners, for the building and ownership of the Leicester Square Theatre, London, and the Imperial in Brighton. The Leicester Square Theatre was bombed during the war and Buchanan lost a sizeable amount of money as a result. However, he went on to manage the Garrick Theatre in 1946, and the King's Theatre in Hammersmith. In the war years The Jack Buchanan Show became popular on the radio (BBC) further increased his appeal. Jack Buchanan Productions (in which his partners were J. Arthur Rank and Charles Woolf) owned Riverside Studios in Hammersmith. Buchanan was legendary among his colleagues for his financial generosity to less prosperous actors and chorus performers.
After the war Jack Buchanan returned to New York and appeared in Harvey (1948). He continued to work on Broadway and the West End and took roles in several Hollywood musicals. In 1951 he had the unenviable task of taking over the lead in King’s Rhapsody after Ivor Novello died. By far his best known film was The Band Wagon (Vincente Minnelli, 1953),), opposite Fred Astaire and Cyd Charisse. He also popped up on television shows in the USA including: Max Liebman's Spotlight in 1954 and The Ed Sullivan Show. In 1955, he performed in the hugely popular eight-part radio series Man About Town.
Jack continued his British film career with As Long as They're Happy (J. Lee Thompson, 1955), and Josephine and Men (Roy Boulting, 1955) featuring Glynis Johns. He made one French film Les carnets du Major Thompson/The Diary of Major Thompson (Preston Sturges, 1955) with Martine Carol .
Jack Buchanan died in London in 1957 from spinal cancer, when he was 66 years old. His whole style was especially notable for a relaxed, affable grace and charm which gave him tremendous sex appeal, but he was also admired by men who envied and hoped to emulate his insouciant savoir faire.