Canary is best known for his roles as ranch foreman Candy Canaday in the NBC Western drama Bonanza, and as Adam Chandler in the television soap opera All My Children, for which he received 16 Daytime Emmy Award nominations and won five times.

[8] He earned a football scholarship to the University of Cincinnati, where he was a three-year letterman from 1957 to 1959 and the recipient of the John Pease Award, as the program's best lineman, in his junior and senior years.

[13] After a semi-regular role as Russ Gehring in the primetime serial Peyton Place, Canary came to international prominence in 1967 on the Western series Bonanza.

[16] Canary guest-starred in the two-part episode of CBS's Gunsmoke entitled "Nitro" (S12E28-29) as George McClaney, a poor man who found high pay creating nitroglycerin.

[17] He also played mobster Frank Gusenberg in the film The St. Valentine's Day Massacre and appeared on the short-lived CBS Western Dundee and the Culhane.

[18][19] A contract dispute that year between Leonard Nimoy and the producers of Star Trek forced Herb Solow, Robert H. Justman, and Gene Roddenberry to compile a list of candidates for consideration to take over the role of Mr. Spock.

Canary's most notable stage performance was on Broadway in the original production of Tennessee Williams's Clothes for a Summer Hotel, which starred Geraldine Page.

[23] A baritone, he also appeared on Broadway with Colleen Dewhurst in Great Day in the Morning, and he did numerous musical stage roles in shows such as Kismet, Man Of La Mancha, The Fantasticks, Sweeney Todd and Carousel, along with dramatic performances in The Seagull, Macbeth, and Clarence Darrow.

He had two short stints on The Doctors as Far Wind, a cult leader who took the hospital staff hostage and killed Melissa Dancy (Dorian Lo Pinto).

Canary's primetime television guest appearances include Law & Order, Touched by an Angel, S.W.A.T., Primus, Alias Smith and Jones, Police Story, Kung-Fu, Hawaii Five-O, Remember WENN, and Cimarron Strip.

In March 2012, David was named as the replacement for the ailing, 90-year-old Jack Klugman in a limited-run production of Twelve Angry Men in New Brunswick, New Jersey.