Dier grew up in Portugal, where he came through the youth ranks at Sporting CP, making his reserve and senior debuts in 2012 after a loan to Everton. In 2014, he moved to Tottenham Hotspur on a five-year contract for a fee of £4 million. He has made over 200 appearances for Tottenham, including in the 2015 Football League Cup Final and the 2019 UEFA Champions League Final.