Williams' final try took his tally to 58 in 87 Tests and was a fitting send off for the wing, who made his debut three weeks short of his 23rd birthday against France in 2000.
And after bringing the curtain down on his international career, Williams admitted playing for Wales was all he'd ever dreamed of.
"Growing up as a child that's the only thing you want to do, play for Wales," he said.
"I have been very privileged and lucky to have that chance. I've had the best time of my life.
"Every time I pull on this jersey it's the best feeling ever. I'm going to miss it.
"It's been a great journey for me.
"I've enjoyed every second of it, the ups and the downs and I just want to say thank you to all the supporters and especially everyone who came along for this game. It's meant a hell of a lot to me."
Williams scored his final try after collecting a long pass from Scott Williams and beating Berrick Barnes to cross the whitewash and celebrate with a forward roll.
"I thought my opportunity had gone to be honest," he added.
"I felt we had an overlap on the right there, but we chucked it up a little bit in the midfield.
"We were given a penalty and I thought that was it, my chance had gone.
"But luckily enough I was on the end of a very good pass and it just took me outside Barnes and inside Ioane and I managed to get to the line again. So I couldn't have scripted the last seconds of that game any better.
"It would have been nice and better to go out in style and to have won the game. It wasn't to be, but I'm immensely proud of the guys."