17th November 2017, 11:01 | Widnes
Inu joined Catalans midway through the 2015 season after a spell in rugby union with Stade Francais and went on to score 14 tries in 46 Betfred Super League appearances.
"I’m very excited to be playing for Widnes Vikings in the Super League next season," said the 30-year-old.
"I know from experience that Widnes Vikings are a tough team to play against and have great supporters, so I am pleased to be joining the team."
Inu, who began his career at Parramatta Eels before spells with New Zealand Warriors and Canterbury Bulldogs, was part of New Zealand's 2008 World Cup-winning squad and has also represented Samoa.
"Krisnan has exceptional playing abilities and understands the English game well," said Widnes head coach Denis Betts.
"He will bring real quality to our edges and I am excited about the impact that he can make on the field.
"Importantly, Krisnan offers real experience too, as someone who has consistently proved himself in the NRL, Super League and internationally.
"I am looking forward to seeing him in action in 2018."