He is best known for playing the handsome, but awkward biology teacher Philip Boynton in the radio and television sitcom Our Miss Brooks opposite Eve Arden.

A native of Lake Bluff, Illinois[2] Rockwell studied at the Pasadena Playhouse College of Theatre Arts, from which he obtained a master's degree.

[3] During World War II he enlisted in the US Navy for four years serving in Washington D.C.[4] After beginning his career as a contract player for Republic Studios he appeared, over his almost 50-year acting career, in more than 350 television episodes and, on stage, opposite José Ferrer in the 1946 Broadway production of Cyrano de Bergerac, and with Ginger Rogers during the 1960s in a San Diego production of Whitfield Cook's play A More Perfect Union.

Rockwell was cast as the Blackhawk Insurance Company's key investigator, Sam Logan, who is assigned to weed out fraud in the payment of claims.

He played standard leads in a couple of anti-Communist-era features, including Republic's The Red Menace (1949) in which he was cast as a returning veteran of World War II who is duped by communists.