The 46-year-old, playing in his 25th consecutive Open, finished in a share of fourth at Royal Portrush after a final-round 73 left him six under.
He briefly got within six shots of eventual champion Shane Lowry after birdies at the second and third but was never realistically in contention for the Claret Jug.
However, it represented his best major finish since coming joint-second in the 2016 Masters and only his second major top five since the 2013 Open at Muirfield.
The veteran, who has a record nine top-three finishes in golf’s premier events, admitted this week he is enjoying his golf more with both girlfriend Helen Storey and son Sam caddying for him.
Westwood, who is tailoring his schedule to reduce the physical toil it takes, has not given up hope of winning a major but accepts The Open probably represents his best chance.
“It was brilliant. How do you sum up a fourth in a major championship?” said the Worksop golfer, whose fall to 78th in the world means he played only the US PGA and Royal Portrush of this year’s majors.
“I missed the cut at the PGA, the golf course didn’t really suit me, and then at The Open I always feel like I can perform.
“I think it doesn’t just suit one style of play. It brings in everybody to it. You don’t have to be a bomber, which I’m probably not any more.
“You’ve just got to have cunning and guile and know how to get your ball around.
“I felt comfortable out there and they were tough conditions.”
Westwood’s last victory came at the Nedbank Golf Challenge, where he beat former Masters champion Sergio Garcia by three, and he feels he still has that competitive edge in him,
“I’m still working hard on everything and I don’t feel like my game is dropping off.
“I feel like I’m still capable of winning tournaments.”
American Rickie Fowler was left to rue an unlucky bounce off a marshal which carried his first tee shot out of bounds and ended an unlikely Open challenge before it had begun.
The 30-year-old’s chances of pulling off a remarkable victory at Royal Portrush were remote to begin with, starting eight shots behind eventual champion Shane Lowry.
However, all that went out the window at the first when he pushed a shot into the right rough and his ball hit a marshal and bounced beyond the white posts, resulting in a double-bogey six.
Fowler was not aware at the time his ball had received extra help on its way out of bounds, which was probably a good job considering his mood.
“I didn’t know until afterwards. That sucks. It’s a good thing I didn’t know, because I probably would have been a little more p***ed,” said the Californian, who carded a three-over 73 to post five under, 11 behind Lowry. “There’s nothing you can do about it, obviously.”