Gillett was probably recruited along with notable co-workers John Foster, Jack King, Isadore Klein, Walter Lantz, Grim Natwick, Ben Sharpsteen and Vernon Stallings.
In 1929, Gillett joined the Walt Disney Studio where he started out primarily working on Mickey Mouse cartoon shorts.
While working there, he directed the Technicolor Rainbow Parade animated shorts featuring Molly Moo-Cow, Toonerville Folks, and several color Felix the Cat cartoons.
[4] In 1934 Gillett shifted the studio production to producing only color cartoon shorts, an innovative step for early animation.
[5] Gillett introduced Disney-influenced ideas, and invited young Disney artists to lecture the New York veterans of Van Beuren.
It didn't help that he fired about fifty people in a six-month period, citing as his reason their failure to meet his standards.
[6] He later discovered that an inker named Sadie Bodin had encouraged female staff members to stand up to Gillett and refuse to do extra work.
On April 17, 1937, Bodin and her husband began picketing outside the studio; for several days they called attention to Gillett firing employees because of their alleged union activity.
He returned to Disney for a time, then moved to Walter Lantz Productions in 1938,[6] where he directed and wrote cartoons, sometimes using the pseudonym "Gil Burton".
Due to his perfectionism, Gillett's shorts at Lantz rapidly ran significantly overbudget and behind schedule, partially contributing to the studio's brief closure in 1940 (after distributor Universal cut the studio's weekly advance, facilitating financial shortages that could not support Gillett's production methods).
Following the Lantz studio's closure, Gillett left the animation business permanently, working at a restaurant by the end of the year.
As confirmed by several golden age animators, among them Shamus Culhane, Bill Littlejohn, Izzy Klein, Grim Natwick and Jack Zander, Gillett was mentally unstable.
[7] Burt's son Ted Gillett(e) was a noted aircraft designer and ham-radio engineer in Southern California, where his family had moved when his father first worked for Disney.