The Queenslander made birdie on the par-5 18th hole in regulation to join final-round playing partner and overnight leader Brendan Steele at 11-under 269.

The extra holes began on the 10th hole in the wet conditions and fading light with Smith holding his nerve with a two-putt par from 10 feet to add to his lone previous PGA Tour title – the 2017 two-man team's Zurich Classic in New Orleans.

Going into Sunday three shots behind Steele, Smith's hopes faded when he made bogey on the 15th to sit two shots off the pace with three holes to play.

Smith, decked out in his trademark final day maroon, played an excellent greenside bunker shot at the 72nd hole to force extra holes with Brendan Stele. PHOTO: Sam Greenwood/Getty Images

However, Steele missed a six-foot par putt on the 17th, and then hit a wild hook from the fairway on the par-5 18th and never had a reasonable look at birdie to open the door for Smith.

The 26-year-old showed his class as he closed for a final-round two-under 68 with an up-and-down from the greenside bunker, capped by a clutch eight-foot putt.

"Just had to hang in there. No one was playing good golf today, it seemed like," Smith said.

"Just hung in there, and what do you know?"

RELATED: TAKE A LOOK IN SMITH'S WINNING BAG

Smith will pocket $1.188 million ($A1.7m) for his first solo PGA Tour win and moved up to fifth in the FedEx Cup standings.

A two-time Australian PGA champion, Smith's career earnings on the PGA Tour have been boosted to $10,645,748 ($A15.4m).

Smith's fellow Australia Cameron Davis carded a 68 to share ninth at seven under, Marc Leishman's 68 left him tied for 28th while Matt Jones had a 70 to slide back to a share of 38th.

FINAL LEADERBOARD

Webb Simpson (67) was third at 10-under while Northern Ireland's Graeme McDowell jumped 19 spots with a 64 to share fourth with Americans Ryan Palmer (68) and Kevin Kisner (69).

A final round in Honolulu that was wet and grey came to life in the final hour, which is about how long it took to play the last two holes because the maintenance crew kept having to squeegee the soaking 18th green.