Aidman graduated from Frankfort High School and attended DePauw University prior to serving in the United States Navy during World War II.

Aidman guest-starred on the NBC children's Western Fury, in episodes of the ABC/WB crime drama Bourbon Street Beat, and in the syndicated aviation adventure series Whirlybirds.

In 1960, Aidman made a guest appearance on the CBS courtroom drama Perry Mason (as murderer Arthur Siddons in "The Case of the Gallant Grafter").

Also in 1963, Aidman was cast as George Ellsworth, an official with the United States Embassy in Warsaw, Poland, in the three-part episode "Security Risk" of the CBS anthology series GE True.

Also in 1963, Aidman adapted Spoon River Anthology by poet Edgar Lee Masters into a theater production.

In 1977, in "The Grim Reaper" episode of M*A*S*H, he portrayed Colonel Bloodworth, a callous, sadistic commander who takes pleasure in predicting casualties and reducing his troops to statistics.

His film roles include Pork Chop Hill (1959), War Hunt (1962), Hour of the Gun (1967), Countdown (1968), Angel, Angel, Down We Go (1969), Tell Them Willie Boy Is Here (1969), Adam at 6 A.M. (1970), Kotch (1971), Dirty Little Billy (1972), Deliver Us from Evil (1973), Twilight's Last Gleaming (1977), Zoot Suit (1981), Uncommon Valor (1983) and Innerspace (1987), his final feature-film appearance.