The 21-year-old former Toronto FC defender from Brampton, Ont., had his work permit approved Monday, paving the way for a move to West Ham United in January.
The east London side currently stands fourth with a 9-4-4 record.
"Absolutely fantastic news for Doneil," said former Toronto FC manager Ryan Nelsen, who recommended the Canadian international to West Ham boss Sam Allardyce. "I know how hard he's worked and the effort he put in."
Nelsen, a big Henry backer, captained Blackburn Rovers under Allardyce.
English reports pegged the West Ham transfer fee at 1.5 million pounds (C$2.7 million).
West Ham had to make its case for a permit before an appeals hearing. Canada's lowly world ranking — currently No. 112 — makes it difficult to secure the proper paperwork in England.
Henry will join fellow Canadian Junior Hoilett (Queens Park Rangers) in England's top flight. The Brampton-born Hoilett has yet to declare his international allegiance, however.
Other Canadians to play in the top tier include Jim Brennan, Terry Dunfield, David Edgar, Craig Forrest, Simeon Jackson, Jimmy Nicholl, Tomasz Radzinski, Paul Stalteri and Frank Yallop.
Calgary-born Owen Hargreaves also played in the Premier League but opted to suit up internationally for England.
The move caps an eventful year for Henry, whose sale to a Cypriot club was shrouded in secrecy for months.
Toronto confirmed in August that Henry had been sold to the Cyprus club in March/April, only to be immediately loaned back to the MLS team. Neither Toronto nor Henry would initially name the team, later identified as Apollon Limassol.
Nelsen said the Cyprus deal was a good one for Toronto, which received both a transfer fee and allocation money. The MLS team also got to hold onto the player for the season, although his rights went to his new club in Cyprus.
At the end of the MLS season, Toronto said Henry's loan period was up but could be extended.
Henry, who has made no secret of his desire to play in Europe, spent 2 1/2 weeks training with West Ham prior to the 2014 MLS season.
"They liked him and a lot of other clubs really liked him as well," Nelsen said Monday from his native New Zealand.
A source told The Canadian Press that top Portuguese side Porto was also interested in Henry.
"He'll go to the top, there's no question about that. He's got all the tools," Nelsen said of Henry in May.
West Ham was clearly more interested in Henry that Toronto, which favoured rookie Nick Hagglund as captain Steven Caldwell's partner in central defence as the MLS season wore on.
Henry was the first player from Toronto FC's academy to graduate to the first team when he signed a pro contract in August 2010.
He went on to play 70 league games, making 19 starts this season.
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