The 31-year-old signed a three-and-a-half-year deal that re-unites him with manager Martin O'Neill, his former boss at Leicester City where he began his career in 1994.
"I am absolutely delighted," O'Neill told Villa's website,
"Emile has been a brilliant player for a number of years and this is great news. It gives us all a big boost.
"He has arrived at a really important time. We have got a bit of momentum going but we haven't the largest squad in the world.
"John Carew is coming back from his back injury but is still a week or two away from being ready to return and Emile couldn't be arriving at a more opportune moment."
Heskey spent six years at Leicester before moving to Liverpool where he played for a further four. He then moved to Birmingham City and then Wigan.
He was an England regular for several years, building up a good partnership with Michael Owen and, after a period out of favour, returned to the side where he has flourished alongside Wayne Rooney.
Last year he earned his 50th cap, though he has managed only five goals in that half-century.
Heskey, whose Wigan contract expired at the end of the season, is O'Neill's first major signing of the January transfer window as he bids to maintain his push for a Champions league spot.
Villa are fourth in the Premier League, three points behind leaders Manchester United.
Heskey is likely to make his Villa debut in next Tuesday's league game at Portsmouth.
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