Chasing South Africa's huge score of 321 for 8 in 50 overs, Pakistan managed 259 in 42.3 overs.
Jonty Rhodes won the man of the match award. A crowd of over 10,000 watched all the excitement.
Cullinan made his second one-day hundred and Rhodes his first. Cullinan's first was also against Pakistan. In making 321, South Africa made their best ever one-day score.
There was rain overnight but the game started spot on and Wasim Akram calling correctly asked the South Africans in, in overcast conditions which were ideal for the Pakistani seamers.
Akram and Younis made use of the conditions to scalp out Hudson, Kirsten and Symcox and at that stage the South Africans were tottering at 38 for 3.
The pitch had uneven bounce early on and all three batsmen fell lbw, Hudson to Younis and Kirsten and Symcox to Akram.
Rhodes joined Cullinan at the fall of the third wicket and what batsmanship they began to put on show. They quietly got on top of the bowling and with some excellent running between the wickets took charge of the proceedings.
They unleashed some lovely and powerful stroke play, with marvellous timing and when ever they pierced the field the ball sped to the boundary. It was classic batsmanship while it lasted and once Akram and Younis rested, the other bowlers just did not have a clue as to how to contain these two batsmen as they went along merrily.
Cullinan was first to his 100 in 101 deliveries with 8 fours. Rhodes got to his three figures in 97 deliveries with 11 fours. Their stand bettered the previous one between Steve Waugh and Dean Jones which was 173 against Pakistan in Perth.
Cullinan was finally out for 124 and Rhodes made his highest one day score before being run out for 121.
When the Cullinan-Rhodes partnership was on show it was apparent that the Pakistanis were badly missing their ace leg spinner Mushtaq Ahmed who has had a knee operation after their tourney in Canada. The Pakistanis also missed Inzamum Ul Haq and Aamer Sohail.
With the latter South African batsmen throwing their bats at everything off spinner Saqlain Mushtaq finished with figures of 3 for 42, while Akram and Younis had two wickets each for 43 and 48.
When Pakistan batted, immediate disaster struck them when quick scoring Saeed Anwar was run out in the first over for one. Elhai played a ball to Jonty and took off.
Rhodes showed why he is the best cover fielder in the world when he swooped down on the ball and in one action hit the wicket with Anwar well out of his ground.
That was a bad omen from which the Pakistanis found difficult to recover, although Saleem Elhai and Ijaz Ahmed tried their best with good knocks of 54 and 88.
The South Africans were well marshalled by Hansie Cronje and with their bowlers and fielders obliging, victory was not long in coming and it did come when De Villiers knocked back Younis' stumps.