Striker Kane, 24, scored 30 Premier League goals as Spurs finished third in the table last season and is about to lead England at the World Cup.
He recently became Tottenham’s leading scorer in the Premier League era.
Kane’s previous contract, which was announced in December 2016 and was reportedly worth more than £100,000 a week, had been due to expire in 2022.
In May, Spurs boss Mauricio Pochettino signed a new five-year deal, keeping him at the north London club until 2023.
Kane finished 2017 as the year’s top goalscorer in European football with 56 goals for club and country.
He broke former England captain Alan Shearer’s record for the most Premier League goals scored in a calendar year, netting 39.