Five players finished level for the lead on 17-under par 265 after 72 holes.
Villegas will be joined by Canada's Mackenzie Hughes, Sweden's Henrik Norlander and American Blayne Barber -- all seeking their first PGA title -- on the tee at the par-3 17th hole Monday morning on the Seaside course at Sea Island, Georgia.
Five players finished level for the lead on 17-under par 265 after 72 holes but American Billy Horschel fell out of the playoff by botching a tap-in par putt on the first extra hole.
"I'm disappointed I'm not still in this playoff but I have a lot to hold my head up about," Horschel said.
Norlander fired a final-round 65 while Barber shot 66, Villegas and Horschel each fired 68s and Hughes, seeking a wire-to-wire win, closed with a 69.
Sharing a distant sixth were Taiwan's Pan Cheng-Tsung and Americans Jim Furyk, Jamie Lovemark and Ollie Schniederjans on 268.
The only member of the playoff lineup with prior PGA playoff experience was Villegas, who lost to American Mark Wilson at the 2007 Honda Classic but defeated Spain's Sergio Garcia at the 2008 Tour Championship.
Villegas has slid to 424th in the world rankings and is playing on a lesser status reserved for past tour event winners, hungry for the tour exemption through September of 2019 that will go to the playoff winner.
The five returned to the par-4 18th for the first playoff hole and all gave themselves birdie chances.
Norlander was just short of the cup on a 30-footer while Barber went a foot past from 25 feet and Horschel did the same from 20 feet. Hughes and Villegas each failed on 15-foot birdie putts. Only Horschel missed his tap-in for par.
"I didn't take my time over that short putt. Simple as that," Horchel tweeted.
The last four returned to the 18th tee for the second playoff hole as the light began to fade and they all reached the green again for birdie attempts in the twilight gloom.
"I'm glad I'm still in there trying," Barber said. "It was pitch black. It was hard to see how it was breaking."
Norlander left his 30-foot birdie try two feet short while Barber slid his 25-footer one foot beyond the cup and Villegas was two feet shy of the hole from 27 feet.
"It was so dark, that last putt I hit, was to the middle of the hole -- hit it firm, I had no clue where it was going," Villegas said.
That left 287th-ranked Hughes, 25, an eight-foot birdie putt to win in only his ninth PGA start, but the ball rolled just off the left edge and he made a two-footer coming back to join the rest in sleeping on the drama.
"I didn't have my best stuff but I showed what I can do," Hughes said. "I made the playoff without my best game and I still have a chance to win. That's all I can ask for."
Villegas, 34, seeks his fifth PGA title after the 2008 BMW Championship and Tour Championship, 2010 Honda Classic and 2014 Wyndham Championship.
Barber, 26, shared third in last year's Honda Classic for the world number 268's best showing in 60 prior PGA starts.
Norlander, 29, is ranked 409th in the world and playing on a sponsor's exemption. His best PGA finish was a share of 15th in 2013 at New Orleans.