"We are delighted to have signed two such outstanding talents," said the Widnes chairman, Tony Chambers, who has already re-signed three former Wigan players - Terry O'Connor, Mick Cassidy and Mark Smith.
Beswick, aged 21, and Allen, a year younger and Widnes-born, join the exodus from Wigan, which now stands at seven of this year's first-team squad.
Promoted Castleford have re-signed two of the young players who helped them return to Super League by winning last weekend's National League One Grand Final. The 21-year-old full-back Michael Platt, and the wing or centre, Michael Shenton, 19, have agreed two-year deals.
Bradford's forward Rob Parker, who is likely to miss out on their Grand Final squad today, has been lined up by Warrington.
The Swinton forward Ian Sinfield will miss watching his brother, Kevin, play for Leeds in the Grand Final at Old Trafford tomorrow after he was called into Scotland's squad for Sunday's European Nations Cup match against Wales.Reuse content