Dwayne Bravo (46) and skipper Darren Sammy (42 not out) pulverised a decent looking bowling in the final three overs as West Indies put up an impressive 166 for six and then shot out the opposition for a meagre 85 in 17.5 overs.
It was the biggest win for the Caribbean side in the Twenty20 format.
Leg-spinner Samuel Badree (3/10 in 4 overs) showed why he is so highly-rated as he decimated the Pakistan top-order with a controlled effort, mixing the skidders with his googlies.
Sunil Narine (3/16) was too good for the middle and lower order as none of the top-eight crossed 20.
Pakistan lost the momentum in the last three overs when Sammy and Bravo took 59 runs. After this, West Indies fielders led by the colourful Chris Gayle also created relentless pressure on the Pakistan batsmen.
While chasing, Pakistan got off to a worst possible start when left-arm seamer Krishmar Santokie bowled a brilliant bowl first up. It was a sharp inswinging delivery to Ahmed Shehzad (0) which hit him right on the toe of his front-foot and umpire Ian Gould adjudged him leg before.
Badree made it two-down in the very next over when Shehzads opening partner Kamran Akmal (0) didnt reach to the pitch of the delivery as he didnt get the elevation and Bravo got a simple catch at mid-off.
The match was as good as over when Umar Akmal (1) was fooled by Badrees googly as Ramdin complete the stumping. It was 9/3 and Pakistan were down in the dumps.
It only got worse when Shoaib Malik (2) stepped out only to miss a Badree delivery and Ramdin got his second stumping of the night. At the end of Powerplay, Pakistan were out of the match with the scoreboard reading 13 for four.
Sammy rightly bowled out Badree in one spell and he had fantastic figures of 4-0-10-3 to show for his efforts.
When Narine came in at the start of the 10th over, Pakistan skipper Hafeez was already batting in 'Test' mode having scrapped around for 31 deliveries scoring only 19 in the process.
His patience gave away as he tried an uncharacteristic hoick off Andre Russell and Chris Gayle took another simple catch at covers.
It was 37 for five and Sohaib Maqsood (18) gave a slog and miss charge to Narine to make it 42 for six as any chances of a miracle ended then and there.
Earlier, a late blitz from Bravo and Sammy helped defending champions put up a fighting total on the board.
Bravo smashed 46 off only 26 balls as he took the attack back to the Pakistan camp with his imperious hitting. He struck two fours and four huge sixes.
He was well-supported by Sammy whose entertaining cameo of 42 was equally important as it helped West Indies reach a decent total after they were tottering at 81 for five.
Sammy struck five fours and two sixes in only 20 balls as the last three overs produced an unbelievable 59 runs.
The turning point in the West Indies innings was the 18th and 19th over bowled by the seasoned duo of Umar Gul (0/29) and Saeed Ajmal (0/41) that produced 45 runs in all.
Till 17 overs, Pakistan bowlers looked in complete control before the carnage from Bravo and Sammy happened at the Sher-e-Bangla Stadium.
Chris Gayle (5) did not fire today as the first delivery he faced from Paksitan skipper Mohammed Hafeez brought about his downfall. Hafeez bowled one wide off-stump which Gayle tried to play with minimal footwork and Kamran Akmal effected a good stumping.
Gayle's partner Dwayne Smith struck two boundaries off Hafeez but was uncomfortable against left-arm seamer Sohail Tanvir's awkwardly angled deliveries. He edged one to Akmal behind stumps as the ball moved away after pitching on the off-middle line.
Lendl Simons (31) struck a few meaty blows but was not able to get the momentum going as he and out-of-form Marlon Samuels could add only 39 in 6.2 overs. Simons struck two sixes before he was unfortunately run-out.
Samuels was once again bogged down but he gave Afridi the charge to hit him down the ground for a straight six. But the veteran leg-spinner had his revenge of his very next delivery. Afridi bowled a faster one and Samuels, who had very little room to play the cut shot, chopped one back on to the stumps.
Reeling at 67 for four in the 11 the over, it soon became 81 for five as Denesh Ramdin (5) tried to slog Babar and was caught at deep mid-wicket by Umar Akmal.
It was then left to Bravo to give the charge and he started by lifting Gul for a big six and followed it up with a pull-shot over deep mid-wicket.