He is the Premiership's top try scorer this season, and possesses explosive finishing skills.
But Vainikolo's selection will court controversy, especially as players such as Josh Lewsey and James Simpson-Daniel have been omitted.
Vainikolo's fellow rugby league recruit Andy Farrell misses out, and there is also no place for Leicester centre Dan Hipkiss.
The uncapped players are Vainikolo, Wasps fly-half Danny Cipriani, Sale scrum-half Richard Wigglesworth and Leicester flanker Tom Croft.
England World Cup captain Phil Vickery is retained as skipper.
Vainikolo is currently in New Zealand, having flown back home last week to deal with what Gloucester termed a "serious family problem".
It is the second time this season he has returned home after his brother passed away before Christmas.
Whether Ashton will unleash Vainikolo on the RBS 6 Nations opener against Wales at Twickenham on February 2 is unclear.
David Strettle and Paul Sackey would appear to be the first-choice wing contenders, and it could be Vainikolo will have to content himself with just being part of the squad.
Bath centre Olly Barkley is another casualty, but Gloucester centre Mike Tindall and Sale Sharks fly-half Charlie Hodgson - who both missed the World Cup campaign - are both back in favour.
There is disappointment, though, for several of England's promising young guns.
The likes of Nick Abendanon, Jordan Crane, Nick Kennedy, Luke Narraway, Tom Varndell and Ryan Lamb are in the England Saxons - formerly England A - squad.
The Saxons play Ireland A at Leicester on February 1, and Italy A in Sicily eight days later.
Six members of England's 2007 World Cup squad have not made it, on top of retired quartet Jason Robinson, Mike Catt, Martin Corry and Lawrence Dallaglio.
They are Lewsey, Farrell, Hipkiss, Barkley, Shaun Perry (injured) and Perry Freshwater.
England 32-man squad for RBS 6 Nations Championship
Backs: I Balshaw (Gloucester), D Cipriani (Wasps), M Cueto (Sale Sharks), T Flood (Newcastle), A Gomarsall (Harlequins), C Hodgson (Sale Sharks), J Noon (Newcastle), P Richards (London Irish), P Sackey (Wasps), D Strettle (Harlequins), M Tait (Newcastle), M Tindall (Gloucester), R Wigglesworth (Sale Sharks), J Wilkinson (Newcastle), L Vainikolo (Gloucester).
Forwards: S Borthwick (Bath), T Croft (Leicester), G Chuter (Leicester), L Deacon (Leicester), N Easter (Harlequins), J Haskell (Wasps), B Kay (Leicester), L Mears (Bath), L Moody (Leicester), T Payne (Wasps), T Rees (Wasps), M Regan (Bristol), S Shaw (Wasps), A Sheridan (Sale Sharks), M Stevens (Bath), P Vickery (Wasps, capt), J Worsley (Wasps).