The actor was in his twenties when he discovered acting. While attending the University of Bridgeport, he played Lennie in a Stamford, CT, production of "Of Mice and Men" (1992) and was hooked. He then attended the prestigious Smith College Masters Program in Theatre and taught acting at the University of Massachusetts, Amherst, before heading to New York in 1978 to appear Off-Broadway in the No Theatre Company's production of "The Elephant Man". After struggling for more work, he was chosen to understudy all 28 male roles for the world premiere of Arthur Miller's "The American Clock" at the Spoleto Festival. When the actor playing the lead became ill following the first night's performance, Smitrovich went on for three nights and so impressed Miller that he was chosen to play the lead in the Broadway run of the play. While TV and film work followed, Smitrovich returned to the New York stage in 1989 as the restaurant worker beaten down by life in Terrence McNally's "Frankie and Johnny at the Claire de Lune".

For TV, Smitrovich made a pilot/TV-movie in 1980 called "The Day the Women Got Even", but his first role of note was in the pilot of "Miami Vice" (NBC, 1984) as Scott Wheeler, Don Johnson's former partner who has gone sour in order to earn more money to help his crippled son. The pathos of the role helped build Smitrovich's profile in Hollywood and led to his casting as Detective Danny Krychek, one of the squad of zealous, hard-bitten cops, in "Crime Story" (NBC, 1986-88). "Life Goes On" followed and, despite a time slot opposite "60 Minutes" that kept it from every really being a ratings winner, lasted four season thanks to a loyal following and a host of strong storylines. The series also helped Smitrovich break into TV-movies. He was the father who wishes to adopt a boy who is divorcing his real parents in "Gregory K", the TV-movie based on the real-life case (ABC, 1993). Also that year, Smitrovich was Ann Jillian's stalwart husband who watches as she becomes pregnant with her son-in-law's sperm in order to give her daughter a baby in "Labor of Love: The Arlette Schweitzer Story" (CBS). Smitrovich later co-starred in the miniseries "Texas Justice" (ABC, 1995). During the first season (1996-97), he was cast as the task force leader ferreting out criminals of the future on Fox's "Millennium".

His feature film work has not been as lasting. Smitrovich made his debut in 1983 playing the small role of a police officer in "Without a Trace". He had bits in "Splash" (1984) and "Maria's Lovers" (1985), as a bartender, before playing a co-starring role in "Band of the Hand" (1986). In 1989, he was a corrupt cop in "Renegades", was Uncle Dave to "The Phantom" (1996) and co-starred in David Koepp's directorial debut "The Trigger Effect" (also 1996).