The home team led 1-0 after the first period, but the visitors equalized through their super-Swede early in the second, and Toronto could go to the break with 4-2 after another goal by Nylander.
In the final act, the teams started with a goal each, and Calgary chased in the final minutes, but never really got close. Instead, the 28-year-old goal king could score his third goal this time.
Tonight's harvest means that Nylander, with a total of 33 goals, climbs to second place in the NHL's goal-scoring league.
Also, Lucas Raymond, Jonatan Berggren, and Elmer Söderblom each scored a goal when the Swedish team Detroit won away against Seattle with 5-4 after penalties.
Corrected: In an earlier version, the incorrect total number of goals for the season for William Nylander was stated.
