Poulter, without a win since 2012, arrived in Houston needing nothing less than victory to qualify for the Masters after missing out by a whisker when he found himself 51st in the world rankings last week.
Ryder's bogey at the short 14th gave Poulter some wiggle room, and normal service was resumed on the 11th, as he holed a seven footer to move three clear again. Hossler's week in Houston shouldn't be remembered by his triple on the lone playoff hole, but rather the fact that he ranked second among the field in SG: Off-the-Tee, fourth in SG: Putting and third in scrambling. "To do it this week, after the disappointment of last week, to know I'm going to Augusta, to do it in true fashion, is unbelievable".
The world No 4, without a worldwide victory since claiming the Open Championship, posted a five-under 67 to get to nine under and stay in touch with midway pacesetter Beau Hossler.
Poulter kept his nerve as he putted from 20 feet which prompted a passionate show of emotion as he beat his chest in celebration.
It must be a Ryder Cup year! I gave Ian the ideal read (for him) to make his putt.
Poulter and Hossler finished 19 under overall, three strokes ahead of Jordan Spieth and Emiliano Grillo in third place.
Attempting to generate a lot of spin with his third shot out of the sand, Hossler flew the green and his ball wound up in the water, all but sealing the victory for Poulter, who could have taken four putts from 33 feet to win the tournament.
Poulter's chances of qualifying for the year's first major, which starts on Thursday, looked remote after he shot 73 on Thursday but rounds of 64, 65, 67 followed after he flicked what he described as a "mental switch".
Poulter then lost his last eight match to Kevin Kisner 8&6. Last week [at the Match Play] was painful and to come here this week, I was exhausted and frustrated. "It's nice to work my way in to contention and if I can improve my position going in to Sunday then I'll have a chance".
"I guess I should never listen to other people", Poulter said.