Inzamam hooked his 86th ball for his fourth boundary to pull off an exciting victory with 10 balls to spare and helped his team gain a 1-0 lead in the five-match series at Iqbal Stadium here on Thursday.
Earlier, Runako Morton top-scored with 43 as the West Indies were dismissed for 151 in 49.5 overs after being sent in to bat.
Inzamam, who was returning from a four-match ban imposed for bringing the game into disrepute during the Oval Test fiasco in August, was scrappy as he took 18 balls to get off the mark and survived some appeals before finishing the game.
The Pakistan captain added 30 with Younis Khan (24) and another 28 with Abdul Razzaq (17) to stave off a valiant challenge by the West Indies, who fought for each run in a low-scoring affair.
West Indian pacemen Corey Collymore (3-19) and Jerome Taylor (3-39) removed the top order but Inzamam came to his team's support.
Pakistan lost opener Mohammad Hafeez in Taylor's first over for nought. Collymore then dismissed Imran Farhat (17) and Kamran Akmal (22) in an incisive six-over spell.
Sent in on a pitch on which strokeplay was difficult, the West Indies lost Chris Gayle (0) off Umar Gul's second delivery of the first over and Lendl Simmons (0) off the last ball of the second over, from Rana Naved-ul-Hasan.
Samuels and Daren Ganga (21) repaired some of the damage during a 46-run third-wicket partnership before first-change bowler Rao Iftikhar had Ganga caught in the covers off a miscued flick.
Master batsman Lara (14) hit Abdul Razzaq for a boundary and was shaping up well before he was run out after being sent back by Samuels while attempting a single in the 30th over -- one of three run-outs in the innings.
Left-arm spinner Rehman removed Samuels and Dwayne Smith (0) in successive overs to finish with 2-20. Samuels hit two boundaries during his snail-paced 86-ball knock of 37.
Morton, however, added an invaluable 57 runs for the seventh wicket with Denesh Ramdin (23), hitting four boundaries in his 66-ball knock. He was the ninth man out, holing out to Naved, who finished with 2-32.
Gul took 2-19 off his 9.5 overs.
The West Indies' total was the lowest in 13 one-day internationals at the venue.
Pakistan were without their key batsman Mohammad Yousuf, who missed the match to be with his wife, who was expecting a child. The West Indies had to leave out star batsman Shivnarine Chanderpaul due to a slight knee injury.
The first match of the series was abandoned without a ball being bowled due to rain at Rawalpindi. The third match will be played in Lahore on Sunday.