The 25-year-old has agreed a one-year deal to link up with the newly promoted club at the Stobart Stadium subject to receiving a visa.
Watts, who parted company with Sydney Roosters without playing a match this season, had agreed to terms with the club last week and tweeted on Sunday: “Really happy to have agreed to terms with ESL club Widnes Vikings on a 1 yr deal. Looking forward to getting my career back on track.”
Watts was recently cleared of assaulting his partner Shannon Kiss after police withdrew the charges against him in August.
“Anthony already has a proven track record in the NRL and he is now backing himself to achieve the same heights in Super League,” said coach Denis Betts on Wednesday.
“At 25, he’s still got a lot of unfulfilled goals and plenty to prove in the game which makes his signing all the more pleasing.”