The Welsh international central defender joins Spurs on a contract until 2025 and will wear the number 14 shirt.
Born in Llangyfelach, a village just outside Swansea, Joe, 22, has progressed through the youth ranks to become a key member of the first team at the Liberty Stadium.
He made his debut in the third game of the 2018/19 Championship campaign against Preston on 17 August, 2018, and went on to make 28 appearances that term.
He followed up with 21 appearances last season and earned his first cap for Wales in a 2-1 victory against Azerbaijan in European Championship qualifying on 6 September, 2019.
Joe, who turns 23 next week, has featured five times for Swansea so far in 2020/21 and started all three of Wales’ matches during the international break against England, Republic of Ireland and Bulgaria to take his tally of caps to seven.