Rose closed with his second straight 7-under 65 on the Marquess Course at Woburn Golf and Country Club to finish at 19-under-par 269, one shot removed from Poulter, who shot 68.
Rose, 21, captured his second title of the year on the European Tour and his fourth worldwide. He won the Dunhill Championship in January, as well as the Nashua Masters on the Sunshine Tour and The Crowns tournament in Japan.
It is nice to win one of the premier events on the European Tour, said Rose. I talked in Germany (two weeks ago) about the fact that although I had won three times this year I hadnt won an event with a full field and full status on the European Tour and I managed to knock that one off pretty quickly.
Rose started the final day three shots behind Phillip Price, and two behind Poulter. He birdied four of his first seven holes for a front-nine 32. However, Poulter maintained a one-shot advantage by carding four straight birdies starting at the fifth for a 3-under 33.
Price, the overnight leader after opening with rounds of 68, 65 and 68, couldnt keep the pace Sunday. He finished with an even-par 72 to claim third place at 15-under 273.
While Price was spinning his wheels, Rose and Poulter were in a dead heat to the finish line.
Poulter edged two ahead with a birdie at the 10th, but Rose came back with a birdie on the very next hole. The two matched each others birdies on the 12th, and when Poulter bogeyed the 13th they were tied at the top.
Rose appeared to have the advantage on the par-3 14th after hitting his tee shot to eight feet, while Poulter found the bunker from the left side of the green. But the 26-year-old holed out from the sand to again match Roses birdie 2.
Rose moved in front for the first time on the 16th after Poulter three-putted. Poulter had the chance to force extra holes on the last when he hit his 7-iron approach to ten feet, but the putt slipped by the left side, giving Rose the crown.
After Ian holed the bunker shot on the 14th and I holed the putt to follow him in we were chatting and saying we had never had so much fun on the golf course, said Rose. He is such a great competitor. (He) plays with so much guts, heart and determination that you never know what is coming next from him.
The three other victories this year have been in far and distant places. Although they are very special it is fantastic to win on home soil.
Said Poulter: I said to Justin when we got into the back nine, 'This is what we play golf for.' I laughed and said, 'Who would have thought that you and I would be coming down the last fighting for it.'
But its great to see him win again this year. I am happy with my performance this week. One more would have perfect but my golf is really in shape and lets hope it continues.
Final results from the British Masters