The Kiwis thus completed their Group B league assignments with two wins and a defeat to sail into the last four stage.
Younis Khan's gamble to field first misfired as Pakistan top and lower half failed against none-too-hostile bowling of the Kiwis.
Scorecard of NZ Vs Pak
New Zealand, earlier asked to bat, piled up an imposing 274 in 50 overs with Fleming hitting 80 and Scott Styris contributing 86.
The 33-year-old Fleming then turned out to be a shrewd tactician as he shuffled his bowlers and made excellent field placing to get Pakistan all out for 223 in 46.3 overs.
This was the second time that the teams were playing each other on this ground and both times the Kiwis emerged winners. Last time, in 1997, they had beaten Pakistan by 22 runs in the Independence Cup.
Though the Kiwis set up a formidable target, Mohd Yousuf and Shoaib Malik raised the vision of Pakistan's spectacular victory but once Shane Bond consumed Yousuf and Daniel Vettori scalped Shoaib Malik, rest of the batsmen just could not cope with the daunting challenge of score 11 runs per over in the last six overs.
Chasing 275 for victory, Pakistan started on blazing note with Mohd Hafeez and Imran Farhat putting up 22 runs off 24 balls before Shane Bond sent Farhat back to pavilion.
Skipper Younis Khan, who had boasted of thriving under pressure, today failed under pressure and scored only two runs before going back. He was snapped at point by Lou Vincent to give Kyle Mills his first wicket and Pakistan were 45 for two in 8.4 overs, Two more wickets fell quickly as Hafeez (43,6x4,46balls) and Shahid Afridi (4, off 6 balls) left with team total reading 83 for four off 16.1 overs.
But Mohd Yousuf and Shoaib Malik put up a heroic stand. The two paced their innings superbly, seeing off dangerous Jacom Oram and tackling the wily spin of Vettori with good footwork before opening up.
The two batted with supreme confidence, belting the bowlers all over the ground. The bowlers found it increasingly difficult to grip the slippery ball. And it looked as the dew will have the last laugh in favour of the Pakistanis.
But suddenly Yousuf lost his cool when there was no need and went to blast Bond only to be caught by Fleming in the covers and the dangerous 97-run fifth wicket partnership came to an abrupt end.
Yousuf, who was at the crease for 124 minutes hit nine fours while facing 92 balls.
Malik then waged a lone battle but the charged up Kiwis mounted pressure on other batmen who could not display the nerves and succumbed to the pressure. Realising that he had to use the long handle to accelerate the run rate, Malik went after the bowlers and paid the price as he was caught by Nathan Astle off Vettori and it was all over bar the shouting for the Pakistanis.
Malik scored 52 (4x4, 70 balls) and when he departed, the score read 202 and the remaing four batsmen lasted only 3.3 overs adding 21 runs.
Bond took three for 45 off 10 overs while Jacom Oram and Kyle Mills scalped two wickets each.
Fleming, leading his side for the record 194 time, also became the most successful captain-batsman in the history of the game as he eclipsed former Sri Lankan skipper Arjuna Ranatunga's record of 5,606 runs.
Before this match, Fleming had scored 5531 but his 80-run knock took his one day total to 5611. Playing in his 256th ODI, Fleming justified his captaincy record with a remarkable innings which came at a time when his team needed it most.
This was New Zealand's 500 ODI and Fleming and Styris rose to the occasion to make it memorable, scoring 80 and 83 respectively and also being involved in a 106-run stand for the fourth wicket.
The dew factor was the main reason for Younis Khan to opt to bowl after winning the toss and his bowlers kept the Kiwi batsmen under leash till the 40th over but in the slog overs the Pakistani bowling disintegrated as they conceded 99 runs in 10 overs taking three wickets.
Earlier, seamers Rana Naved and Umar Gul gave Pakistan early breakthrough scalping two wickets in quick succession to reduce the Kiwis to 23 for two in just seven overs.
Twenty two-year-old Gul drew the first blood for his side when he clean bowled Lou Vincent (2) of his second ball. Rana Naved then sent Nathan Astle (15) back to pavilion when he had the batsman caught in the slip by Younis Khan.
The Pakistan seamers continued to trouble the Kiwi batsmen but Fleming displayed tremendous concentration to keep the scoreboard moving. He put up a 37-runs with Peter Fulton (7) for the third wicket before Rao Ifthkhar trapped Fulton leg before. At that stage, the Kiwis were reeling at 60 for three in 14.1 over.
Then came the Kiwi fightback as the skipper was joined by 31-year-old Scott Styris.
The two started cautiously and took time to settle down. Run rate did slow down considerably but once they got themselves entrenched, the scoreboard started moving fast.
The Kiwi start was slow indeed. The first 10 overs of power play saw 43 runs on the scoreboasrd, next one yielded only 19 and in the third and last five overs of power play only 15 runs were scored.
As Fleming and Stryis started building their innings, they were also helped by lady lluck and survived a scare when the score was 94 for three. Styris, who was on 16, flicked Abdul Razzaq towards suare leg and charged out for a run. The ball was stopped by a diving Imran Farhat who threw it back to wicket keeper Kamran Akmal.
Akmal needed to remove the bail but to the surprise of all he tried to wreck the stumps with a big throw only to see it missing the target. It was the easiest possible run out chance which he missed and after that there was no looking back for Styris.
Fleming and Styris put on 108 runs for the fourth wicket in 23 overs and when the partnership looked assuming dangerous propositions spinner Shoaib Malik broke it.
Fleming, who looked all set for his hundred, played a casual shot and Malik took a fine diving return catch.
The skipper's knock 0f 80 came off 105 ball and was studded with one six and eight boundaries. At that stage, the score was 168 for four off 37.1 overs.
But Styris was there and he rose to the occasion. He got good support from other lower order batsmen and the Kiwis went on rampage in the slog overs as Pakistani bowling suddenly disintegrated.
Styris went after the bowling and he was followed by other batsmen as the Pakistanis were sent on a leather hunt.
Jacom Oram (31,1x6,4x4, 26 balls) and Brendan McCullum (27,1x6,3x4,13 balls) added to the woes of Pakistanis.