The 25-year-old had eight goals and 26 assists in 49 games for the Houston Aeros of the AHL. He was called up when the Wild were short-handed on the blue line during the postseason.
A sixth-round pick in the team's inaugural draft eight years ago, Reitz was second among Houston defenseman with a plus-11 rating last season.
Even after trading for Marc-Andre Bergeron on Tuesday, the Wild have a roster spot or two open on defense.
Brent Burns, Kim Johnsson, Nick Schultz and Martin Skoula are under contract, but Keith Carney and Sean Hill will be unrestricted free agents. Petteri Nummelin has already signed with a team in Switzerland. Kurtis Foster is recovering from a broken leg and his return is uncertain.