The five-year agreement represents the American company's largest European team sponsorship and could be worth up to ?10m a year to the club.
Beginning with the 2012/13 season Under Armour, who currently supply the Wales national rugby team, will replace Puma in providing Tottenham's playing kit and training wear, as well as replica shirts.
Big money: Tottenham train ahead of their clash with AC Milan after announcing their new kit deal
Speaking about the deal, Tottenham chairman Daniel Levy said: 'We are delighted that Under Armour will become our new technical partner from 2012 onwards.
'They are an extremely ambitious brand with global aspirations, making them ideal partners for Tottenham Hotspur.'
?Spurs boss Redknapp says it's 'touch and go' whether Bale will face MilanBerbatov always knew Spurs star Bale would be one of the world's bestI almost quit! Defoe reveals frustration at Tottenham's squad rotationAll the latest Tottenham news, features and opinion
?Explore more:People: Daniel Levy Places: Wales
Source: Daily Mail
Source: Daily Mail