Darvish (4-0) yielded only one run on four hits, striking out nine while walking two. He threw 62-of-97 pitches for strikes and lowered his ERA to 2.18.
The former Japanese star, signed by Texas to a six-year, $60 million contract in January, has fanned 33 batters over 33 innings in his five major league starts.
Joe Nathan sealed the victory with his sixth save.
Mitch Moreland and Craig Gentry each socked a solo homer for Texas, which improved to 17-6 while taking the first of a three-game series in Canada.
Blue Jays starter Kyle Drabek (2-2) fanned eight over six frames, allowing a pair of runs on five hits.
Edwin Encarnacion homered in his fourth straight game, connecting on a solo shot in the fourth for Toronto.