[2][3] Co-creator of Rankin/Bass Productions with his friend Jules Bass, he created stop-motion and traditional animation features such as Rudolph the Red-Nosed Reindeer, Frosty the Snowman, Santa Claus Is Comin' to Town, and the 1977 cartoon special of The Hobbit.

[2][7] The two worked closely together for many years, co-directing and producing a wide array of stop motion animated features and cartoons, which Rankin had referred to as "Animagic".

[2] In addition to directing, Rankin primarily created the script and sketched the character concepts, which would be made into the wooden puppets by Japanese artists, including head supervisor and partner, Tadahito Mochinaga.

[2] Some of the most famous features were the holiday-themed TV specials,[7] such as Willy McBean and His Magic Machine, Rudolph the Red-Nosed Reindeer, Santa Claus Is Comin' to Town, Rudolph's Shiny New Year, The Year Without a Santa Claus, Frosty the Snowman, 'Twas the Night Before Christmas, and Jack Frost.

[2] He is also credited with devising the story for many Rankin/Bass productions, including the feature films The Daydreamer and Mad Monster Party?.

[7] Referring to him as an "animation legend", The Hollywood Reporter noted that during his career, Rankin worked with actors such as Jeff Bridges, Mia Farrow, Angela Lansbury, Alan Arkin, Danny Kaye, James Cagney, Fred Astaire, Boris Karloff, Tallulah Bankhead, George Burns, John Huston, Burl Ives, James Earl Jones, Christopher Lee, Walter Matthau, Vincent Price, and Flip Wilson.