Set just 136 to win, Pakistan openers Sharjeel Khan (59) and Khalid Latif (59 not out) shared a blistering first-wicket stand of 107 that all but sealed victory.
Pakistan finished on 139 for one with 31 balls to spare as they gave Sarfraz Ahmed a win in his first match as Twenty20 captain.
Earlier England, fielding the same side that lost to the West Indies in the last over of April’s World Twenty20 final, managed just 135 for seven after winning the toss.
Wahab Riaz took three for 18 and spinner Imad Wasim two for 17 as England hit just one boundary in the last 10 overs of their innings.
Openers Alex Hales (37) and Jason Roy (21) were the only England batsmen to pass 20 as Pakistan, who shared the Test series 2-2 and lost the one-dayers 4-1, had a night to remember under the Old Trafford floodlights.