Roberts was in his second season with Bath after joining from Harlequins, but will leave the Gallagher Premiership club to join the South African side, based in Cape Town.

The 33-year-old won the last of his 94 Wales caps in November 2017 against New Zealand.

Roberts also played three Tests on two British and Irish Lions tours.

"It is bittersweet because Bath has been an amazing place to live and play," said Roberts.

"I have loved my time and being involved in some pretty special games.

"It is tough to leave and today was very difficult on my last day having to stand up in front of the lads and thanking them and I got quite emotional."

Bath have signed Fiji centre Josh Matavesi from Newcastle Falcons to help plug the gap created by Roberts' departure.

Stormers say Roberts will also act as a mentor and has joined the side through the financial support of a corporate partner.

"The Stormers got in touch and they were looking for a bit of experience to their backline," said Roberts.

"I have toured South Africa with a load of sides and it's a place that resonated probably because rugby is at the heart of what it is about.

"It is their national sport and it reminds me of Wales how passionate they are about the game.

"In life and in a rugby career these opportunities don't come away very often.

"It is an opportunity that won't come my way again now I am 33 and probably only have a couple of years left in my career.

"It is a chance I can't not take because I would have to live with that regret if I don't do it."

The centre was named Lions man-of-the-series in South Africa in 2009 and scored a try in the victorious series decider against Australia in Sydney four years later.

Roberts had hoped to be selected by new Wales coach Wayne Pivac, but was not named in the 38-man squad for the 2020 Six Nations.

Stormers open their Super Rugby campaign on 1 February with a home match against Hurricanes. The South African side are captained by Springbok World Cup winning skipper Siya Kolisi.