Tamim formed two partnerships to complete the chase, a 41-run opening stand with Munim Shahriar (21 off 21 balls) followed by an unbroken 89-run unbeaten partnership with Mahmudul Hasan Joy (38 off 42 balls) which took Khulna home comfortably.
Earlier, Pakistani pace duo of Wahab Riaz and Amad Butt ransacked Rangpur’s batting line-up, bowling them out for 129 in 20 overs.
Wahab claimed 4-14 while Amad took 3-16 as Rangpur folded for a meagre total after being asked to bat first.
All-rounder Mahedi Hasan top scored for Rangpur with 38 off 34 balls.
With the win, Khulna jumped to fifth place in the seven-team points-table while Rangpur remained third with four points in four games.