The 2003 season was the Detroit Lions' 74th season in the National Football League, their 70th as the Detroit Lions, and their first under head coach Steve Mariucci. The team improved upon their 3–13
The Lions signed cornerback Dré Bly, a highly touted free agent, to a five-year, $24.5 million contract.
In his sophomore season, quarterback Joey Harrington started all 16 games for Detroit, throwing a career high 22 interceptions.