Australian prop Ben Cross has signed a short-term deal for Wigan until the end of the season, and will then join Widnes for their 2012 campaign.
The 32-year-old is a former Grand Final winner with the Melbourne Storm and will join Vikings on a one-year deal once he finishes his stint at Wigan.
Widnes have also captured second-row forward Hep Cahill from Crusaders.
Cahill, 24, helped Melbourne win the World Club Challenge against Leeds in 2010 and has signed a three-year deal.
Widnes coach Denis Betts, who will lead the Vikings on their return to Super League after they were elected back in March, said he was delighted to capture the pair.
"Ben will bring a massive appetite for work and an enormous amount of enthusiasm with him, in both a playing and mentoring capacity," said Betts.
"He's determined to play in Super League and his age dictates that he's motivated and ready to kick on for the duration of his one-year contract.
"Hep fits the bill entirely," Betts continued. "He comes with a great pedigree and has been well educated through his time at a really strong environment in Melbourne.
"He's already an outstanding young player with a tremendous appetite for work but there's still bags of unfulfilled potential in him.
"As pleased as we are to be welcoming him here, he's just as excited about joining a club that can put a platform in place to help him excel even further."