His 104-ball innings, containing 13 fours and eight sixes, was the highest individual score in a final, bettering his captain Ricky Ponting's 140 not out against India four years ago. Gilchrist reached his century from 72 balls, 10 faster then West Indies captain Clive Lloyd in the 1975 final against Australia, with eight fours and six sixes.
He put on 172 for the first wicket with Matthew Hayden (38), another World Cup final record, to propel Australia to 281 for four from their 38 overs in the rain-reduced match.
Gilchrist, out for one in each of his last two innings, scored fifties in both the last two World Cup finals. Australia were bidding for an unprecedented third World Cup title running at the Kensington Oval.
Both openers watched Lasith Malinga's opening overs carefully on a pitch unaffected by morning rain but enjoyed themselves at the other end at Chaminda Vaas's expense.
Gilchrist lofted successive balls to leg for four and six in the left-armer's second over, glanced another four off his third and Hayden slashed his first boundary over point.
Dilhara Fernando replaced Vaas, whose first three overs had cost 24, at the Joel Garner End. Hayden slogged a four over mid-wicket and Gilchrist flat-batted a further boundary over mid-off in the pace bowler's next over.
Fernando dropped a difficult low caught-and-bowled chance off Gilchrist on 31 and the batsman responded with two fours and a towering six over long-on from the next three balls.
Gilchrist brought up his half-century from 43 balls and went on to the attack again with two towering sixes in an over off Tillakaratne Dilshan.
Another Gilchrist six over long-off off Fernando followed by a four brought up the century partnership from 102 balls and the return of Malinga, whose first four overs had cost six runs, only hastened the run rate.
Hayden slogged the fast bowler's first ball for six and Gilchrist brought up his hundred with another boundary.
Records continued to tumble as the pair passed Mike Brearley and Geoff Boycott's 129-run opening stand for England against West Indies in 1979 before Hayden was caught in the covers by captain Mahela Jayawardene off Malinga with the score on 172.
Gilchrist was out one short of his 150, caught off a skier off Fernando, leaving time for Ponting to score 37 including a six over long-on off Malinga before he was run out
Australia 281 for 4 in 38 overs (Gilchrist 149, Hayden 38, Ponting 37; Malinga 2 for 49, Fernando 1 for 74) Vs Sri Lanka (yet to bat).