Ameche was born in Kenosha, Wisconsin to Felix Ameche, an immigrant from Italy whose original surname was "Amici", and Barbara, who was of Irish and German descent.

Ameche began his career in vaudeville with Texas Guinan until Guinan dropped him from the act, dismissing him as "too stiff". He made his film debut in 1935 and by the late thirties had established himself as a leading actor in Hollywood. He appeared successfully in such films as Alexander's Ragtime Band (1938), as Alexander Graham Bell in The Story of Alexander Graham Bell (1939), and Heaven Can Wait (1943).

He was so associated with his role as Bell that for a time, "Ameche" was slang for telephone. By the end of the decade his films had lost appeal, and he turned to radio where he achieved great success during the fifties playing opposite Frances Langford in The Bickersons.

He was married to Honore Prendergast from 1932 until her death in 1986, by whom he had six children, one of whom was Ron Ameche, who owned the restaurant "Ameche's Pumpernickel" in Coralville, Iowa. Ameche's late younger brother Jim Ameche was also an actor.

For three decades he was virtually absent from films, until he was cast alongside fellow veteran actor Ralph Bellamy in the film Trading Places in 1983. The actors played rich brothers intent on ruining an innocent man for the sake of a one-dollar bet. The film's great success, and their acclaimed comedic performances, brought them both back into the limelight.

In an interview some years later on Larry King Live, co-star Jamie Lee Curtis stated that Ameche, a proper old-school actor, whose script called for him to use the "F-word" at one point, went to everyone on the set and apologized ahead of time, for being compelled to use such a harsh vulgarity in their presence.

Ameche's next role, in Cocoon (1985), won him an Academy Award for Best Supporting Actor. He continued working for the rest of his life (including a role in the sequel, Cocoon: The Return). His final scenes for the film Corrina, Corrina (1994) were completed only days before his death in Scottsdale, Arizona from prostate cancer.

For his contribution to radio, Ameche received a star on the Hollywood Walk of Fame at 6313 Hollywood Boulevard. and a second star at 6101 Hollywood Boulevard. for his contribution to the television industry.

Ameche died on December 6, 1993. He was buried at Resurrection Catholic Cemetery, a.k.a. St. Philomena Cemetery , in Asbury, Iowa.