One week after Poulter was mistakenly told he had locked up a spot at Augusta National through the world rankings, he left no doubt by winning with a clutch moment reminiscent of his Ryder Cup heroics from Medinah in 2012.
Both men played reasonable drives at the first extra hole but Hossler sent his second into the bunker before mishitting his third shot into the water, effectively leaving Poulter with three putts to win.
Hossler, after posting 4 consecutive birdies on the back-nine in the final round, came within an inch of sinking a lengthy birdie putt to win the event after entering the 18th hole with a one stroke lead at 19-under-par overall.
Jennifer Song dropped out with a par on the third playoff hole, and Park and Lindberg chose to take one more trip down the par-5 18th in fading light.
Poulter finished the day tied with American Beau Hossler on 14 under par ahead of the final round, knowing that a only victory will earn him a place at Augusta next week. With a one-shot lead, he had a chance to clinch the victory on the 18th in regulation, but his 30-foot birdie putt trickled over the right edge of the cup.
That has happened four times since 2008, when Augusta National offered invitations to winners at full PGA Tour events: Johnson Wagner (2008), Matt Jones (2014), Jim Herman (2016) and Henley past year.
The Englishman had carded scores of 64 and 65 in his previous two rounds and he maintained his fine form as he made a flying start with birdies at the second, fourth and sixth to open up a three-shot cushion.
Ian Poulter, who said last week after the WGC Dell Match Play that he wasn't sure he was going to play this week, showed up.
"He thought he had holed it".
"I didn't play my best stuff".
"This one's for Katie, my wife", Poulter said.
NOTES: Phil Mickelson shot bogey-free 67 Sunday to finish in a tie for 24th at 10 under. Jennifer Song dropped out with a par on the third extra hole, and Park and Lindberg chose to play one more hole in fading light. Defending champion: Russell Henley.