Shehzad smashed 98 to follow on from his 70 on Friday which had set Pakistan up for a 25-run victory in the first game of the tour.
On Saturday, he followed that up with 98 not out as the tourists clinched a 19-run win and 2-0 series sweep.
The right-hander struck six sixes en route to the highest score by a Pakistani batsman in the Twenty20 format, but missed an opportunity to reach three figures when he could only manage a single from the final ball of the innings. After Pakistan finished on 179 for one, with skipper Mohammad Hafeez unbeaten on 54 from 40 balls, Zimbabwe mustered 160 for six in reply.
Although Pakistan made a circumspect start after being put in to bat, scoring 37 for one in the opening six overs as Nasir Jamshed was dismissed for 23, Shehzad opened up beautifully from the ninth over and regularly found the boundary.