MEMPHIS, 14 Jun 2015 (AFP) - Gomez, who shared the overnight lead with Owen, finished with a 72-hole total of 13-under 267, while Owen -- who led by two through seven holes -- finished with an even par 70 at TPC Southwind for 271.
Gomez finished with a flourish, rolling in a 30-foot putt for his fifth birdie of the day at the final hole.
He became the first Argentinian since Angel Cabrera at last year's Greenbrier Classic to win on the US Tour.
Five-time major champion Phil Mickelson, tuning up for the US Open that starts on Thursday at Chambers Bay in Washington state, gave himself some momentum with a final-round 65 that left him in a group sharing third on 272.
"I'm feeling a lot better about heading into the US Open after this week than I did after last," said Mickelson, who had eight birdies and three bogeys on Sunday.
Mickelson was joined on eight-under by South Korean Noh Seung-Yul, who also carded a 65, Australian Matt Jones (68), and Americans Michael Thompson (66) and Brooks Koepka (70).
Reigning FedExCup champion Billy Horschel also closed with a 65 to share eighth place on 273. He was in a group that included Boo Weekley, Chad Campbell and Scotland's Russel Knox.
Leading final-round scores on Sunday in the US PGA Tour St. Jude Classic (USA unless noted, par-70):
267 - Fabian Gomez (ARG) 66-68-67-66
271 - Greg Owen (ENG) 64-70-67-70
272 - Phil Mickelson 68-69-70-65, Noh Seung-Yul (KOR) 69-72-66-65, Michael Thompson 69-69-68-66, Matt Jones (AUS) 69-67-68-68, Brooks Koepka 64-67-71-70
273 - Boo Weekley 67-70-71-65, Billy Horschel 71-67-70-65, Russell Knox (SCO) 70-64-73-66, Chad Campbell 69-66-70-68
274 - Will Wilcox 68-72-69-65, Colt Knost 72-64-72-66, Chez Reavie 70-70-66-68, Tom Hoge 69-65-71-69, Chris Smith 67-67-71-69, Scott Brown 65-69-68-72
275 - Cameron Percy (AUS) 69-69-71-66, Vaughn Taylor 67-74-68-66, Billy Hurley 72-66-70-67, Camilo Villegas (COL) 71-68-66-70
276 - Steven Bowditch (AUS) 69-71-70-66, Alex Cejka (GER) 71-68-69-68, Steven Alker (NZL) 65-68-74-69, Spencer Levin 67-68-72-69, Kevin Chappell 71-64-71-70, Ryan Palmer 64-71-70-71, Austin Cook 68-64-72-72