This was Quetta’s first win in the tournament. Whereas, Karachi have now lost three matches in a row.
Chasing a target of 169 runs, Karachi were restricted to 162-5 in their allotted 20 overs.
Kings all-rounder Shoaib Malik remained unbeaten on 71 runs in 49 balls but was not able to get his side over the line. His innings included eight fours and a six.
Meanwhile, Irfan Khan was not out on 37 runs in 26 balls with the help of one four and three maximums.
Karachi made a poor start to the run-chase after three quick wickets. Sharjeel Khan and Haider Ali were both dismissed for a duck, while James Vince, who seemed to be in control briefly, could only score 22 runs in 14 balls.
Malik and Irfan threatened to chase down the target, after adding 86 runs in 54 balls for the sixth wicket, but Quetta’s bowlers, especially Naseem Shah and Mohammad Hasnain, held their nerve in the death overs to ensure that their side ended up winning the match.
Hasnain was the pick of the bowlers with figures of 2-29 in four overs. Meanwhile, Naseem, Qais Ahmad and Mohammad Nawaz claimed one wicket each.
Earlier, Opener Martin Guptill scored a ton as Quetta Gladiators recovered against Karachi Kings after losing quick wickets.
Quetta posted 168-7 in 20 overs after being asked to bat first by Karachi.
Guptill smacked pacer Andrew Tye for 30 runs in the 19th over of the innings to reach his century.
The New Zealand cricketer scored 117 runs in 67 balls, with the help of 12 fours and five sixes, and was dismissed on the final ball of the innings.
Quetta were reeling after Karachi captain Imad Wasim bagged impressive figures of 3-16 in four overs, which included wickets of Jason Roy, Abdul Bangalzai and Umar Akmal.
Iftikhar Ahmed was the second-highest run-scorer in Quetta’s innings after scoring 32 runs in 27 balls.
Pacer Aamer Yamin also claimed 3-37 in four overs.
Quetta Gladiators: Jason Roy, Martin Guptill, Abdul Bangalzai, Sarfaraz Ahmed(w/c), Umar Akmal, Iftikhar Ahmed, Mohammad Nawaz, Odean Smith, Qais Ahmad, Naseem Shah, Mohammad Hasnain
Karachi Kings: Sharjeel Khan, James Vince, Haider Ali, Matthew Wade(w), Irfan Khan, Shoaib Malik, Imad Wasim(c), Aamer Yamin, Andrew Tye, Mohammad Amir, Imran Tahir.