Lebanon,[4] Betz began his amateur acting career at the age of 10, when he formed a theatrical company with six friends who performed plays in his grandmother's basement.

[6] Beginning in 1942, Betz served three and a half years in the U.S. Army during World War II, seeing action in North Africa and Italy.

[7][4][5] Betz made his Broadway debut in 1952 in The Long Watch,[8] and toured with Veronica Lake in the summer-stock play, The Voice of the Turtle.

Prior to his eight-year run on The Donna Reed Show, Betz made guest appearances on such television series as Sheriff of Cochise, Perry Mason, Gunsmoke (as Nate Timble and Ned Glass, an outlaw trying to go straight under an assumed name in the 1957 episode “Gone Straight” - credited as “Carl Bentz”), The Millionaire, and Alfred Hitchcock Presents.

Alex was often called upon to rescue wife Donna Stone (Reed) from awkward situations and to monitor the behavior of their children, Mary (Shelley Fabares) and Jeff (Paul Petersen).

Jeff Stone introduced the sentimental hit song "My Dad" in a 1962 episode, specifically singing the tune to Betz.

In 1964, he appeared as Reverend T. Lawrence Shannon in a limited stage run of The Night of the Iguana, for which he earned excellent reviews.

Betz initially thought the role was for a guest spot, but soon realized Monash had proposed that he star in a new series.

[11] He also made many guest appearances on a variety of popular television shows, such as Mission: Impossible, The Mod Squad, Love, American Style, and Starsky & Hutch.