The 27-year-old defenseman has 10 points (five goals, five assists) and a plus-17 rating in 40 games this season. He could have become an unrestricted free agent after the season.
Selected by the St. Louis Blues in the third round (No. 82) of the 2014 NHL Draft, Walman has 22 points (nine goals, 13 assists) in 116 regular-season games with the Red Wings and Blues and no points in one Stanley Cup Playoff game.
Walman is the second defenseman the Red Wings signed in the past two weeks; Olli Maatta signed a two-year, $6 million contract ($3 million AAV) on Feb. 16. Maatta, who could have become a UFA, has 18 points (five goals, 13 assists) in 55 games this season, his first with Detroit.
The Red Wings (28-23-8), who have won seven of their past 10 games, are three points behind the Pittsburgh Penguins for the second wild card into the playoffs from the Eastern Conference.
Detroit visits the Ottawa Senators on Tuesday (7 p.m. ET; TSN5, RDS, BSDET, ESPN+, SN NOW).