Dale Steyn took 3-15 in his four hostile overs as Pakistan were restricted to 98-9 -- their lowest Twenty20 total against South Africa -- after they won the toss and opted to bat.
South Africa easily reached the target in 14.3 overs with opener Quinton de Kock hitting a 38-ball 48 not out while skipper Faf du Plessis making an unbeaten 37 knocking off the runs without being troubled by Pakistan's spin-packed attack.
The second and final Twenty20 will also be played in Dubai on Friday.
De Kock hit three boundaries and two sixes off 38 balls while Du Plessis hit four boundaries and a six off 40 deliveries as South Africa made short work of their opponents.
Pakistan's batsmen once again failed to fire just as they did in the 4-1 one day international series defeat.
Umar Akmal with a 41-ball 49 was the only batsman to put up any resistance in an otherwise chaotic batting display in which four batsmen failed to score after Pakistan won the toss and decided to bat.
Paceman Lonwabo Tsotsobe chipped in with two wickets for the cost of just nine runs in his four tight overs, while Dale Steyn chipped in with two early wickets as Pakistan were reeling at 4-3.
Umar added 29 for the sixth wicket with Abdul Razzaq who made 10, before finally getting run out. He hit four boundaries and a six.
Shoaib Malik made 12 while Shahid Afridi scored ten.
Paceman Lonwabo Tsotsobe and Imran Tahir took two wickets apiece.
Pakistan's previous lowest T20 total against South Africa was 119 which they made at Abu Dhabi in 2010.