Nazir struck 14 fours and eight sixes in 160 from 121 balls to lift Pakistan to 349 in 49.5 overs after they were sent in to bat.
Zimbabwe had crashed to 30 for three in the 10th over, then a 2-1/2 hour stoppage for rain meant they had to chase a revised target of 193 from 20 overs before they were dismissed for 99 in 19.1 overs.
Only four Zimbabwe batsmen got into double figures - Elton Chigumbura top-scored with 27, including three consecutive sixes off Danish Kaneria, Stuart Matsikenyeri made 18, Brendon Taylor got 13, and Sean Williams 11.
Shahid Afridi, playing his first match of the competition, after serving a four-match for a breach of the ICC Code of Conduct in South Africa last month, was the most successful Pakistan bowler with three wickets for 20 runs from four overs.
Umar Gul collectd two for 10 from five overs, and Kaneria bagged two for 48 from four overs.
Inzy bids tearful adieus: Earlier, a tearful exit from ODIs for Inazmam-ul-Haq was overshadowed by Nazir's hundred. Inzamam delighted the modest crowd with a brief cameo of 37 off 35 balls, but Nazir brought the curtain down with some enterprising strokes.
Last Sunday, Inzamam announced that this match would be his last ODI for Pakistan, and he would also give up the post of national captain following the World Cup and the death of coach Bob Woolmer.
When he arrived, Nazir was well into stride, but he joined in the fun with two fours and three sixes before he skied an on-drive to extra cover off Tawanda Mupariwa in the 28th over.
As Inzamam retreated to the dressing room, the celebrating Zimbabwe players all rushed to shake his hand, pat him on the back, and hug him to offer their congratulations for a stellar ODI career in which he played 378 times and scored 11,739 runs at an average of 39.52.
Meantime, his Pakistan teammates had descended the steps to the dressing room to form a receiving line, and Inzamam, usually a stony-faced character, began to wipe away the tears they too began to applaud him.
By the time Inzamam departed, Pakistan were well in control, and Nazir never took his foot up off the throat of the Zimbabwe attacked.
After Kamran Akmal was caught behind for 15 off Elton Chigumbura in the seventh over, and Shoaib Malik was caught at backward point for 21 in the 18th over, Nazir drove Utseya to long-off for a single to reach his 50.
After he and Inzamam put on 70 for the third wicket, Nazir was dropped on 81 at deep mid wicket, when Friday Kasteni put down a skier off Gary Brent, who had Mohammad Yousuf was caught and bowled for three off the very next delivery to leave Pakistan 170 for four in the 31st over.
Nazir was eyeing his landmark and reached his milestone, when he played forward defensively to Christopher Mpofu, and scampered a single to the short cover fielder. Younis Khan had come to the wicket and was playing fluently before he too, was dropped on 26 by keeper Brendon Taylor off Sean Williams essaying a reverse sweep.
Younis went on to add 81 for the fifth wicket with Nazir before he was run out for 28 to leave Pakistan on 251 for five, with 10 overs remaining.
Nazir jammed his foot down hard on the accelerator and continued to maraud the the Zimbabwe attack. After he was Nazir dropped on 135 at long-on by Chigumbura off Mupariwa, he flicked the same bowler through square leg for a single to reach his 150.
Pakistan however, continued to lose wickets, but they gathered 98 runs for the loss of their last five wickets from the last 10 overs, with Nazir dismissed for the highest individual score by a Pakistani in World Cup cricket, and Iftikhar Anjum collecting a career-best 32 off 16 balls.
Both Pakistan and Zimbabwe failed to qualify for the Super Eight quarter-final stage of the competition.