William Clay Ford, the club's owner and chairman, also announced the promotion of Tom Lewand to team president and the promotion of Martin Mayhew to general manager.
Besides Marinelli, also let go were assistant director of pro personnel Dave Boller, and assistant coaches Joe Barry (defensive coordinator), Mike Barry (assistant offensive line) and Jimmy Lake (secondary). Joe Cullen's (defensive line) contract will not be renewed, while Jim Colletto was re-assigned to offensive line coach.
The Lions' winless season capped Marinelli's three-year tenure. He compiled a 10-38 record.
The 10-year defensive assistant in Tampa Bay was the fourth head coach in former General Manager Matt Millen's eight years in Detroit's front office.
The Lions were the first team since the 1976 Tampa Bay Buccaneers, who went 0-14 in their expansion season, and the first team since the league went to a 16-game format to finish a full season without a win.