Wyatt had rallied from four shots back Saturday on the back nine of Chenal’s Bear Den Course to force the playoff.
Williamson and Wyatt began the day tied and each shot a final round 5-under, 67, as did playing partner Daniel Berger — who missed the playoff by one stroke and finished third.
The win qualified Williamson for the Arnold Palmer Invitational next spring in Orlando, Fla. — provided he remains an amateur.
Talor Gooch of Oklahoma City and John Catlin of Gold River, Calif., finished tied for fourth — 12 shots behind the leaders.
Ollie Schniederjans, the first-round leader, settled for a tie at ninth. The former Harrison High School golfer and rising Georgia Tech sophomore shot 72 and finished at 2-under 286 for the tournament.
Schniederjans won’t have long to rest, however, as he will compete with a large number of other local players in a U.S. Amateur qualifier Tuesday at Piedmont Driving Club in Atlanta.