The 20-year old Spurs right-back joins on loan for the rest of the season to lift some of the gloom surrounding under-pressure Villa manager Gerard Houllier.
As an extra bonus for Houllier, White Hart Lane counterpart Harry Redknapp has given his permission for Walker to play in the FA Cup, starting with this weekend's tricky third-round tie at Bramall Lane.
In great form: Kyle Walker (left) has helped QPR to the top of the Championship table
Walker said: 'I'm excited about being here and proving that I'm good enough to play in the Premier League.
'That's why Tottenham bought me from Sheffield United and that's what I'm keen to show here at Villa.
'This is a great opportunity for me and I'm looking forward to taking it.
'I know several of the players here from England Under-19s and England Under-21s - Nathan Delfouneso, Ciaran Clark and Marc Albrighton.
'I'm sure those lads will help me to settle in and enjoy my time at Villa.
'I'm really keen to contribute and compete and prove myself here.'
Villa manager Gerard Houllier said: 'We're pleased that Kyle will be with us until the end of the season.
'He is 20 years old, an attacking full-back and a very promising young player. He will be a valuable addition to our defence.'
History boy: Kyle Walker (left) became the youngest Sheffield United player to play at Wembley in 2009
Though the loan is scheduled to last the rest of the season, Redknappcould have stipulated Walker should not become cup-tied, in case Tottenham encounter injuries or suspensions later in the competition andhave to recall him.
But he gave his approval for the stylish former Sheffield United defender to return to Bramall Lane and bolster Houllier's hopes of a Cuprun that could turn round Villa's fortunes and help safeguard him from the sack.
Walker has spent this season loan at Championship leaders QPR where he has been outstanding in his 17 matches.
In May 2009 he became the youngest Sheffield United player ever to play at Wembley as his side lost the Championship play-off final to Burnley.
Ex-Liverpool boss Houllier again come under fire from disgruntled fans, after his side sank into the bottom three in the Barclays Premier League with a 1-0 home defeat by Sunderland.
He claimed he still had the support of his Villa bosses, but he must sense a revival has to be launched swiftly to prevent his reign being cut short, just four months after he was brought back to the Premier League.
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Explore more:People: Gerard Houllier, Harry Redknapp Places: Liverpool