The deal is worth $850,000, according to Cap Friendly. Gagner was set to become an unrestricted free agent after playing out the final season of a three-year, $9.45 million contract signed with the Vancouver Canucks.
Gagner joined the Red Wings prior to this season's trade deadline in a move that sent Andreas Athanasiou to the Edmonton Oilers. The 31-year-old suited up in six games for Detroit before the pause, notching a single goal while averaging just over 15 minutes per night.
The Red Wings, who finished the shortened season in 31st place, have over $34 million in projected cap space this offseason with a few key restricted free agents to sign, including forwards Tyler Bertuzzi and Anthony Mantha.