Matt Duchene sent Mason Marchment on a two-on-one break which ended when he hit Seguin with a crisp pass and the Dallas centre made no mistake, firing the puck past an outstretched Hellebuyck.
Joe Pavelski had the other Stars goal.
Jake Oettinger turned aside 27 shots for Dallas, who moved to 12-6-2.
There was no scoring in the first period.
Connor Hellebuyck made 19 saves for Winnipeg, who dropped to 12-7-2.
Winnipeg has dropped their last two games after a five-game winning streak.
There was no scoring in the first period.
Matt Duchene nearly got the Stars on the board just under nine minutes into the second period when he broke in alone on Hellebuyck but ended up crashing into the net.
The Jets got a two-man advantage 10:17 into the second period for just over a minute but failed to score.
Dallas got on the board first 12:54 into the second when Roope Hintz cut by the net and slid the disc to a wide open Joe Pavelski who beat Hellebuyck with a low shot.
The goal was his 10th of the season.
Winnipeg had a two-man advantage for 44 seconds 4:17 into the third but were unable to score.
Tyler Seguin scored at 16:45 of the third when he converted a Mason Marchment pass on a 2-on-1 break, lifting the puck just past an outstretched Hellebuyck to make it 2-0 Dallas.
SHOTS-DALLAS 21 WINNIPEG 27
ATTENDANCE-11,439