Broadhurst fired a final-round, 5-under 67 to reach 17-under-par 271 for the tournament -- the same score he shot to win this event last year.
Last year's victory was Broadhurst's first in a decade, and it came only after Barry Lane and Paul Lawrie faltered down the stretch. In this win -- the sixth of his career -- it was Broadhurst who nearly coughed up the winner's check.
Broadhurst, 40, bogeyed 17 to fall into a tie with clubhouse leader Wall, coming up just right on a 25-foot par putt. He then knocked his second shot at 18 over the green and into the gallery.
Maybe a disastrous situation for some, but not for a player with Broadhurst's short game. His pin-seeking chip ended just over a foot from the hole, and the European Tour veteran calmly rolled in the birdie putt.
'I tried to play it like it was a normal day, and just chip it down there,' Broadhurst said afterward. 'It wasn't that difficult of a shot, I didn't think.'
Easy shot or not, the chip ended Wall's chances to possibly come away with win No. 2 in a playoff. The 2000 Alfred Dunhill Championship birdied 18 and also fired a 5-under 67 in the final round to get to 16-under-par 272.
Andres Romero finished one stroke further back in third place after a 6-under 66. Overnight leader Ricardo Gonzalez managed just a 1-under 71 and ended up in a fourth-place tie with Charl Schwartzel (68) at minus-14.
In the third round, Gonzalez tied the course record with an 8-under 64 to snatch the lead from Broadhurst, who had led since the first round after also matching the course record.
But while players like Gonzalez were settling for pars and the odd birdie, Broadhurst was making strides on the front nine.
After beginning his round in second place at 12 under, Broadhurst birdied four consecutive holes from No. 2 to reach minus-16. The first three birdies all came on par 4s, the fourth on the 493-yard, par-5 fifth.
Broadhurst added another birdie at the par-4 seventh to make the turn at 17 under. After another birdie at 12, Broadhurst led by three shots over Romero until a double bogey at 13 whittled his advantage to just a stroke.
However, Romero bogeyed 16 ahead of the final group, while Broadhurst birdied the par-4 14th. With his lead again at three shots -- this time over three players -- Broadhurst was afforded some comfort.
It didn't last -- his par try at 17 just missed the hole -- but Broadhurst managed to rally, and his birdie at 18 was his fourth straight on the 476-yard finishing hole.
'I made it hard down the stretch, but I didn't really hit too many bad shots,' said Broadhurst. 'I knew Wall had birdied 18 and I knew I needed a birdie at the last to retain [the title].'
The long-hitting Gonzalez said after Saturday's round that the Le Meridien Penina course wasn't really set up for a player of his style. It was better suited for short hitters and good putters.
Indeed, Broadhurst fit into one of those categories this week. He needed just 25 putts or less in three of his four rounds, and never once three-putted.
'I just changed something on the putting green, just a slight technical change,' Broadhurst admitted. 'I was getting a great roll from distance. It was fantastic.'
Jose Manuel Lara finished alone in sixth place at minus-13 after a 6-under 66 on Sunday. Markus Brier and Mattias Eliasson were two strokes further back after matching 69s.