Peshawar will now meet Karachi Kings today in the second Eliminator, with the winners earning the right to meet Islamabad United in the final on March 25 in Karachi.
In yet another last-ball finish, Quetta Gladiators required 24 runs off the final over to reach the winning target of 158 set by Peshawar.
With the crowd cheering loudly, Anwar Ali hit the first ball from spinner Liam Dawson for a boundary and then blasted the next for six.
He failed to score off the third ball but hit two sixes off the next two to put Quetta on the brink of victory.
Quetta needed three runs from the final over and two to force the match into the Super Over, but Anwar failed to clear the boundary with another lofted shot and his partner Mir Hamza was run out as they went for the second run.
Anwar remained unbeaten on 28 off 14 balls. Earlier, Mohamed Nawaz and Sarfraz Ahmed contributed 35 each in the Quetta total.
Peshawar Zalmi, who were asked to bat first by Quetta, scored 157 all out with Englishman Dawson top-scoring with 62 off 35 balls which included six fours and four sixes.
Tamim Iqbal and Mohamed Hafeez made 27 and 25, respectively. Rahat Ali claimed four for 16 for Quetta.
Winning captain Darren Sammy said: “Needing 25, you tend to back your own team. The games against Quetta are always excellent, the crowd was great too, and honestly, a win is a win. At the start of the tournament, we lost some players. So, credit goes to these guys.
“Our coaches worked with the boys, and today, I needed them to step up. Dawson the way he batted, without that innings we wouldn’t be here today. We enjoy this win, but need to take on Karachi again. Got to come back and do the basics right. Hopefully, we can continue this.”
Quetta skipper Sarfraz Ahmed said: “The match was in our hand, and I feel we lost the game because of our own errors. If we were sensible off the last ball, we could’ve had the super over, but the pressure got the better of the boys at the end.
“The way the pitch was, it didn’t matter whether we batted first or second today. Our journey this year has been full of ups and downs, but Nadeem (our owner) has been excellent. Hope to come back stronger next year.”