Frazar bested Robert Karlsson in the marathon final round, earning the 39-year-old his first taste of victory and breaking the sixth-longest active streak without a win on the PGA Tour.
Frazar almost lost to Karlsson on the final hole of regulation after finding water and carding a bogey to finish at 3-under 67.
But it turned out to be enough to match Karlsson's 13-under 267 and force a playoff after the Swede finished with a round of 2-under 68.
Both golfers earned pars on each of the first two extra holes and then proceeded to No. 12 at TPC Southwind in Memphis. Karlsson was unable to make a par putt on the hole, but Frazar easily two-putted for victory.
It was Frazar's first Top 10 finish since late 2009, while Karlsson lost the St. Jude event in a playoff for the second straight year.