The 22-year-old former Liverpool trainee Hammill has signed a three-and-a-half-year deal with the Molineux club.
Hammill, who has also had spells with Dunfermline, Southampton and Blackpool, has been Barnsley's stand-out performer this season, netting eight goals for the Championship club.
Winging in: Adam Hammill is presented at Wiolves' training ground following his £500k move from Barnsley
The winger is in training with Mick McCarthy's side for the first time today ahead of Saturday's game with Liverpool, the club where he started his career and could make his first start for Wolves.
'I'm really delighted to be joining Wolves,'the England-under-19 international told the club's official website.
'Wolves are a massive club and I'm looking forward to playing my part for the rest of the season.
Joining the pack: Ex-Liverpool trainee Adam Hammill has left Barnsley for Wolves
'I'm pleased to be getting the chance to try and play Premier League football.
'My agent has got a few players here already and they all say how much they enjoy playing here under Mick and the staff here.
'It seems a really good working environment and I can't wait to get going and get the shirt on.
'I've spoken to Mick on the phone and am looking forward to meeting him today.
'I've heard he's honest and will tell you things you don't want to hear at times but he's straight down the middle and fair which is what everyone wants as a player.
In demand: Matthew Jarvis is being watched by Liverpool and Everton
'I think my ambitions go hand in hand with the club.
'I'm really keen to play in the Premier League and the club are keen to establish themselves here and I'm really excited about the prospect.'
But his arrival will prompt speculation that the highly-rated Matt Jarvis could be on his way out of Wolves with Liverpool and Everton among his admirers.
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