Poulter birdied three of his final six holes at Is Molas to pip Brand by a single shot at 21-under-par. Brand's Sunday 66 bettered Poulter's final-round score by three shots, but a bogey on the 72nd hole left him one shot shy of a playoff.
Poulter began the final round with a three-shot lead, but found himself trailing by two following 12 straight pars. The 24-year-old Englishman finally set his wheels in motion by birdying the 13th, and then added another red number at the 15th. Poulter finally drew even with his Scottish counterpart by carding his third birdie in five holes at the 17th.
Playing in the group in front of Poulter, Brand Jr., failed to get up and down from the greenside bunker on the home hole for a bogey 5. Brand dropped to 20-under and was forced to watch from the sidelines as Poulter two-putted for a par 4, and a 1-shot victory.
'It feels absolutely fantastic,' said Poulter. 'It was a slow start. Three shots in front makes it very difficult as you are always waiting for someone else to make a charge.'
Poulter collected $140,000 for his triumph. In the process, he moves to 29th on the Volvo Order of Merit. Poulter now leads Alastair Forsyth in the race for Rookie of the Year honors. Both men are in next week's Volvo Masters.
'I knew I was behind Alastair coming into this week,' Poulter said. 'I knew I had to play well. There is still next week to go, but this puts me nicely in front. I just want to try and get in contention next week.'
Francisco Cea and Richard Green tied for third at 18-under-par. In the season's final full-field event, Cea jumped from 136th on the Order of Merit to 106th. The top 115 earn their 2001 European Tour cards.
'There was a lot of pressure. A lot of pressure all week,' said the Spaniard. 'But I'm very happy now. Very happy.'
Green's third-place finish means he he'll be making the trip to Montecastillo, Jerez, Spain. The top 55 in earnings qualify for the Volvo Masters. Green now stands in 54th place.