The 33-year-old has won 92 caps to date for his country and played in four tests for the Lions on two tours. He spent the last year playing for Kubota Spears in Japan.
He made his debut against the Barbarians in 2012 and last turned out in a Welsh jersey in the summer against South Africa at Twickenham and in the two tests ‘down under’ against Australia.
He first joined Saracens in 2017, and in the 2019-20 season he helped the north London club to complete the Premiership and European Champions Cup double.
“The last few weeks have been a whirlwind for me in all honesty. My pregnant wife and I recently made the difficult decision not to return to Kubota Spears for a second season, a club that welcomed me so warmly 12 months ago after the World Cup,” said Williams.
“One of the Sarries management contacted my agent to see if I would be interested in finishing the season with them due to injuries within the squad, and it didn’t take long to say yes.
“I thoroughly enjoyed my previous time with the club. It was a special time in both my career as well as the club winning multiple trophies, and the unique culture of the club left a mark with me.
“I can’t wait to join the squad, following the birth of my first child, and help them achieve their goals.”
Saracens director of rugby Mark McCall is pleased to be bringing Williams back to StoneX Stadium for a second spell.
“Liam had an incredible impact on our group both on and off the pitch during his first spell at Saracens. He is a world class player who has been at the top of his game for well over a decade now,” said McCall.
“The opportunity to bring Liam back to the club was a no brainer for us and we can’t wait to see him back in the Saracens shirt.”