Kavanagh, 23, joined the Vikings initially on loan from Wigan in 2008, and has been one of their stand-out performers in the past four seasons.
Widnes Director of Rugby, Paul Cullen, said: “Ben has successfully delivered potential into performance from Academy to Championship level on a consistent, durable basis. We have no doubt that he can be challenged to repeat this at Super League level.”
The Halifax-born forward, who is on a run of 72 consecutive games for the Vikings, has now signed a deal until the end of 2014.
Kavanagh said: “I’m really enjoying myself at Widnes and I have done since day one, that’s why I’ve signed this extended deal with the club.
“Before looking too far ahead, we’ve already got a great squad in place and despite a few set-backs, we’re definitely heading in the right direction. At the end of the day, the players want what the fans want and there’s no reason why we can’t go further this season and in the years to come.
“Performing in front of the Vikings’ fans is a special experience for me and something I look forward to doing each and every week and hopefully we can go on to achieve big things together.”