Scott was unable to make any early progress on day four but birdies at his final four holes saw him break clear of a race for second and third place and he earns the US$750,000 second placed cheque.
Rose, 38, has spent most of the past eight years among the top 20 in the world, a majority of that time in the top 10.
That's how good Rose was, and if the victory doesn't rank up there with him capturing the 2013 U.S. Open or the Olympic gold medal in the 2016 Summer Games, it will be cherished for the company he kept and the track on which he excelled.
Tiger Woods (67) tied for 20th at 10-under in his first start of the year.
That left him tied with Ryan Palmer (67) and Rahm, who had two birdies and two bogeys in his even par round on the South Course - a far cry from his sparkling 62 on Thursday. "Twenty-one under around Torrey Pines is great golf", Rose said. "I love winning on great tests of golf and this one will give some special feelings because of that". I won't look at the leaderboard.
Scott completed the front nine in par with a bogey on the fifth hole and a birdie on the ninth.
Pelicans star Anthony Davis wants out of New Orleans, requests trade
Per Wojnarowski, it's expected that almost every team in the National Basketball Association will try to make a move for Davis. Boston could agree to a Davis trade before July 1 that isn't finalized until after that date. "I can say that to the world".
Scott badly missed the fairway on the par-five 18th and had to lay up from a bunker, and Rose stuffed his wedge in to three feet to wrap it up. "I just hope that the iron shots get a little bit better tomorrow".
"Got to have these little goals when I'm not in contention to win a tournament", Woods said.
Quiros had an ugly end to his round, making double-bogey at the par-5 last after finding the water surrounding the green off his second shot, hitting his fourth shot into thick rough at the back of the green, and then duffing his chip. He finished runner-up, two shots back at 19-under.
"It was nice to shake off some rust and see what I need to work on", Woods said after his first official PGA Tour event. Torrey Pines is tough enough to not have allowed a third-round leader to close one out since Woods in 2008. Today, I tried to at that point.
Justin Rose admitted he "can't believe" how good he played with new clubs as he won the Farmers Insurance Open to become the PGA Tour's most successful Englishman.
The combination has the former world No.1 convinced he can break his win drought of nearly three years and return to golf's top ranks.