Gilder, who needed playoffs to capture his first two titles of the season in consecutive weeks in late July, avoided extra holes by rolling in a four-foot knee-knocker at the final hole.
'I made things interesting at the end by leaving that first putt short,' Gilder said of his two-putt par at the 18th. 'Luckily I got the next one in.'
Bland, a 56-year-old South African with a slew of victories around the world, was in position to win his sixth Senior Tour event and his first since 1996. He began Sunday's round with a two-stroke lead but shot a 1-under 70 that featured a costly bogey at the par-4 17th.
'I'm quite happy with my game at the moment,' said Bland, whose second-place finish was his best of the season. His previous best showing of 2002 was a tie for third at last week's Uniting Fore Care Classic.
'There are lots of wonderful players out here. Your game has to be in top form and you've got to putt under pressure.'
Gilder, who opened with two birdies Sunday to tie Bland at 11-under, later took his first lead with a 12-foot birdie putt at the 13th. Bland matched his playing partner at 13-under when he wedged his third shot to six feet at the par-5 15th hole and sank the putt for birdie.
Both players had birdie chances at the par-3 16th -- the hole Bland aced on Saturday en route to his career-best 63 and the second-round lead -- but missed their putts and settled for pars. Bland then seemed to have the upper hand at the par-4 17th when he found the fairway off the tee and Gilder drove into the right rough.
But Bland missed the green right, executed a mediocre chip to 12 feet and two-putted for bogey. Gilder, who knocked his approach to 18 feet, took two putts to get down for a par and led by one shot with one hole to play.
'I didn't feel comfortable shooting at the flag at 17 and pushed it to the right a little bit,' Bland said.
'John left himself with a tough chip at 17. The rough is pretty gnarly,' said Gilder. 'I felt good after he missed his putt there.'
Needing a birdie to tie Gilder at the last, Bland drove into the rough but managed to save par with a six-foot putt. Gilder put the pressure on himself when he left his first putt a couple of feet short of tap-in range, but he stepped up and split the cup to seal the win.
Gilder, who won twice last year and garnered the Senior Tour's 2001 Rookie of the Year award, now has a total of five victories on the 50-and-over circuit. He racked up six wins on the PGA Tour.
Hale Irwin, the Senior Tour's all-time wins leader who tops the 2002 season money list, was in the mix at 11-under after his third birdie of the day at the 13th. However, he hit his tee shot onto a trap at the par-3 14th and wound up carding a five. Irwin finished with a two-under 69 and tied for third place with Bruce Lietzke (67) at 10-under 203.
'It was a killer,' Irwin said of the 14th hole. 'I hit a bad shot and then had a tough bunker shot. Three putts later, I walked off with a double-bogey.'
Irwin, who is tied with Gilder for the most victories of 2002 with three, has 11 finishes in the top-three and 18 in the top-10 in 21 starts.
Final results from the Allianz Championship