Bernard's first role in a feature film was a cameo in the Charles Bronson film Death Wish, and his first major role was in the 1974 movie Thomasine & Bushrod. He later appeared in Car Wash, WarGames, No Way Out, While You Were Sleeping, and Blue Thunder.

Bernard was born in Chicago, Illinois. His first starring role was in the pilot episode of the television series The White Shadow as Jim Willis. His other well-known TV roles are in the 1980s TV series Cagney & Lacey as Inspector Marquette from 1982–1983, Days of Our Lives as Preston Wade in 1982, and a recurring role in the first season of Night Court as Judge Stone's arrogant rival Judge Willard. His big role came in the 1983 hit NBC miniseries V as Caleb Taylor. Bernard reprised his role in the 1984 sequel V: The Final Battle. His other big TV role was in the 1990s FOX comedy series Herman's Head as Herman's boss, Mr. Paul Bracken. He appeared in the video games Wing Commander III: Heart of the Tiger and Wing Commander IV: The Price of Freedom as Captain william Eisen.

Shortly after the filming of Liar Liar was completed, Bernard suffered a heart attack on October 16, 1996. He had been driving his car in Burbank, California when he was stricken, and was involved in a rear-end accident. Bernard was rushed to Providence St. Joseph's Medical Center in Burbank where he died. He was survived by his wife Debra and son Jason Jr. His body was cremated. Liar Liar was dedicated in memory of him.

He played the blind musician Tyrone Wattell in the film All of Me. Bernard's final appearance was in the 1997 film Liar Liar as Judge Marshall Stevens.