Watson finished the tournament at 12-under 272, two shots clear of runners-up Kevin Na and Tony Finau.
Scott continued to look uncomfortable with his swing and made the cut on the number before posting back to back weekend rounds of even par to finish T53.
Watson took the lead going into the final round after an excellent third round 65.
Of the other Australians, Adam Scott has improved to one over the card while playing his back nine and the 2005 victor is five shots ahead of countryman Greg Chalmers (six over). Watson hit too big of a fade toward the left pin, and it came up short and into the bunker. He fired out from the hazard, the ball struck the pin and disappeared into the hole. He made two bogeys in his first six holes to give up his lead. Hyejin Choi (67) pulled within one shot at the turn, but Ko made birdie on No. 9 and pulled away with two more birdies to win by three shots over Choi. Another safe par on the final hole saw him lifting the trophy.
His T14 Finish in California also had a significant impact on his FedEx Cup position, the four time TOUR victor moving from 103 to 86 on the standings.
Ed Sheeran Explains His Silver Ring at BRIT Awards 2018
The show also included a cover of Nina Simone's " It's a New Dawn ", and a reggae take on his global hit, " Shape of You ". Ed has been dating his former school friend Cherry since 2015, hinting early in 2017 that he was ready to settle down.
ADELAIDE, Australia (AP) - Jin Young Ko of South Korea, playing in her first event as an LPGA Tour member, closed with a 3-under 69 to complete a wire-to-wire victory in the Women's Australian Open. Ben Hogan and Lloyd Mangrum are the only other three-time winners at Riviera. Nobody thought Bubba Watson from Bagdad, Florida, could ever get to 10 wins.
"My goal has always been to get to 10 (wins)", a misty-eyed Watson said in a greenside interview. "So many emotions going through my head right now", Watson said, choking back tears. "I feel like I played better than finishing whatever it is, 25th or whatever it's going to be". So you never know if that was going to be the last time. The UCLA alum could do no better than pars the rest of the way for a 71 to tie for fourth with Scott Stallings (68). All four had a chance to win but all four came up just shy of Bubba's four-round total of 12-under.
Phil Mickelson also was in the hunt. On the back nine, he made three birdies, including a key one on the 16th, where he made a 30-foot putt. The 39-year-old truly shined in all facets of the game, not ranking lower than 21st in any Strokes Gained category - including second in SG: Tee-to-green, and sixth in SG: Around-the-green - and also displayed fantastic accuracy, ranking in a tie for the 27th in fairways hit, and the seventh for GIR.
It's been a pedestrian start to the season for Baddeley whose only top-10 in nine events prior to this week came in Las Vegas last November.
"I'm playing well enough to compete week in and week out now", Mickelson said. "I'm not searching anymore".