The 1973 Baltimore Colts season was the 21st season for the team in the National Football League. Under first-year head coach Howard Schnellenberger, the Colts finished with a record of 4 wins and 10 losses, tied for fourth in the AFC East with the New York Jets. The Colts lost the tiebreaker to the Jets based on head-to-head sweep (0–2).

Baltimore was the only team to lose to the Houston Oilers, bowing 31–27 in week eight at home. The Oilers broke an 18-game losing streak with the victory.

Hired in February, Schnellenberger was previously the offensive coordinator with the Super Bowl champion Miami Dolphins,^[1] who went undefeated in 1972 under head coach Don Shula.

This was the first year since 1955 in which long-time quarterback Johnny Unitas was not on the Baltimore roster.

Before the season, the Colts traded long-time quarterback Johnny Unitas to the San Diego Chargers. Unitas had been splitting quarterback duties with Earl Morrall and Marty Domres over the past few seasons; he played one season for San Diego and retired.