It was Wallstedt’s first shutout of the year and the second of his career.
Matt Boldy had a goal and an assist, and Marcus Johansson, who played his 1,000th NHL game, extended his point streak to a career-high nine games for the Wild (7-7-3), who have won two straight and four of their past five.
Devin Cooley made 17 saves for the Flames (4-11-2), who have been shut out in back-to-back games following a 4-0 loss to Chicago on Nov. 7.
Cooley kept it scoreless with a glove save on a Jonas Brodin slap shot at 12:36 of the first period.
Wallstedt denied Jonathan Huberdeau on the breakaway at 5:02 of the second period to keep the 0-0 score.
Boldy gave Minnesota a 1-0 lead, finishing a give-and-go from Johansson up the slot at 13:47. Johansson has 11 points (five goals, six assists) in the streak.
Kirill Kaprizov scored into the empty net at 19:10 of the third period for the 2-0 final.