West Indies slumped to their eighth successive one-day defeat, going down to Pakistan by 40 runs in the second match of the series at the Beausejour stadium in Gros Islet, St Lucia on Saturday.
The home side, chasing a victory target of 259, were bowled out for 218 in 48.2 overs.
Shahid Afridi returned figures of four for 38, including a double-wicket maiden in his sixth over, as Pakistan took an unbeatable 2-0 lead in the three-match contest.
It is the first time Pakistan have defeated West Indies in a one-day series in the Caribbean, although they won a triangular competition in 2000 involving Zimbabwe.
"We are playing our best cricket for a while," vice-captain Younis Khan told reporters.
"I think the tough tours to Australia and India have helped us gel as a team and believe in ourselves. Those tours were a turning point for us."
The defeat equalled the longest losing streak for West Indies, who were also beaten in eight consecutive games in 1999-2000.
Chris Gayle gave the hosts a good start to their innings with a breezy 43 from 45 balls before he was bowled by seamer Shabbir Ahmad with a delivery that pitched outside leg stump and jagged back to hit off.
Ramnaresh Sarwan was run out for 17 by a direct hit from Younis at mid wicket.
West Indies skipper Shivnarine Chanderpaul (three) was also run out four overs later after Runako Morton had called for a suicidal single.
Morton tried to make amends with his maiden half-century but he became the first of Afridi's two victims in the sixth over when he was clean bowled for 55.
Afridi followed up by trapping Dwayne Bravo lbw for a duck to leave West Indies 163 for six.
The Pakistan spinner also bowled Wavell Hinds for 22 before dismissing Ian Bradshaw for five.
Earlier, Pakistan's total was built around a knock of 51 by skipper Inzamam-ul-Haq, another 51 from Shoaib Malik and 48 by Younis.
Inzamam, who was struck in the groin area by a full-toss from spinner Gayle, had to retire hurt briefly and did not take the field when West Indies batted.
Paceman Corey Collymore took three for 40.
Younis will lead Pakistan in the first Test in Barbados in the absence of Inzamam, who will serve a one-match ban for excessive appealing in India.
"It is a dream come true to get the chance to lead Pakistan in a Test match. But my main ambition is to lead Pakistan to a win in Barbados as we have never won a Test series in West Indies," said Younis.
The third and final match of the one-day series is in St Lucia on Sunday.
S. Butt run out 16
S. Afridi c W. Hinds b Powell 12
S. Malik run out 51
Y. Youhana c Browne b W. Hinds 21
Inzamam-ul-Haq c Bravo b Gayle 51
Y. Khan c Gayle b Collymore 48
A. Razzaq b Collymore 20
K. Akmal not out 24
Naved-ul-Hasan c&b Collymore 1
I. Anjum not out 1
Extras: (lb-1, nb-1, w-11) 13
Total: (for 8 wickets, 50 overs) 258
Fall of wickets: 1-27, 2-33, 3-81, 4-136, 5-186, 6-222, 7-255, 8-257.
Did not bat: S. Ahmad
Bowling: Powell 7-1-27-1 (nb-1, w-2), Bradshaw 7-0-27-0 (w-4), Collymore 10-1-40-3, W. Hinds 6-0-38-1, Gayle 10-0-50-1 (w-1), Bravo 10-0-75-0 (w-3).
C. Gayle b Ahmad 43
X. Marshall c Butt b Naved-ul-Hasan 7
R. Sarwan run out 17
R. Morton b Afridi 55
S. Chanderpaul run out 3
W. Hinds b Afridi 22
D. Bravo b Afridi 0
C. Browne b Naved-ul-Hasan 35
I. Bradshaw b Afridi 5
D. Powell b Anjum 6
C. Collymore not out 0
Extras: (b-7 nb-13 w-5) 25
Total: (all out, 48.2 overs) 218
Fall of wickets: 1-25, 2-67, 3-93, 4-114, 5-163, 6-163, 7-172, 8-192, 9-218, 10-218.
Bowling: Naved-ul-Hasan 6.2-0-20-2 (nb-2, w-1), Ahmad 7-0-38-1 (nb-1 w-1), Anjum 9-0-35-1 (nb-1, w-1), Razzaq 6-0-32-0 (nb-5, w-1), Afridi 10-1-38-4 (nb-2, w-1). Malik 10-1-47-0 (nb-2, w-1).
Result: Pakistan won by 40 runs.