At the age of 14, he left school to work in an automotive garage, where he served as chauffeur and valet for British actor Frank Pettingell.

Cabot stated later in a 1968 interview that he believed acting was a type of lying, and he had gained a smoothness in his speech while serving as Pettingell's dressing room butler.

[2] His formal acting career began with a bit part in Foreign Affaires (1935); his first screen credit was in Alfred Hitchcock's Secret Agent (1936).

Post-war, Cabot landed roles in such British films as Third Time Lucky (1949), The Spider and the Fly (1949), as the villainous Fouracada in Dick Barton Strikes Back (1949); he was also in Ivanhoe (1952) and The Love Lottery (1954).

He appeared in a couple of international productions, the Spanish-UK-USA Sinbad comedy Babes in Bagdad (1952) and the Italian version of Romeo and Juliet (1954) as Lord Capulet, before moving to the United States, where he worked for Disney on Westward Ho, the Wagons!

[citation needed] Cabot had a two-year period as one of the three leads as college professor Dr. Carl Hyatt on the detective show Checkmate (1960–1962).

[4]: 1590  As Checkmate fit into the CBS Saturday schedule, Cabot appeared as Eric Whitaker in the 1960 episode "Five O'Clock Friday" on the ABC adventure series, The Islanders.

[4]: 1043  In 1965, Cabot played a role on The Beverly Hillbillies as Lucas Sebastian, a billionaire entrepreneur who wanted Jed Clampett to invest in his new venture of undersea farming.

Cabot received another role as the host (Winston Essex) of Ghost Story (1972), a supernatural anthology (it was retitled Circle of Fear after he left the show).

The role required Cabot to shave the trademark beard he sported since 1957 as makeup crews were unable to make it look Santa-like.