The move carries a neat family twist, given Upson is the son of former Arsenal and England defender Matthew Upson, who made 57 appearances for the Gunners between 1997 and 2003. Spurs will receive a training compensation fee for the teenager, according to Fabrizio Romano, given his age and the terms of his departure from the club.
Chelsea, Manchester City and Everton were among the Premier League clubs credited with interest in Upson, while Bayern Munich, Borussia Dortmund, Bayer Leverkusen and Monaco had also been credited with interest from abroad.
Reports suggest Upson made his final decision after visiting Arsenal's London Colney training base and discussing his options with his family, with the club's track record of promoting academy talent under Mikel Arteta said to be a significant factor.
A versatile defender capable of playing centrally or at right-back, Upson made 34 appearances for Tottenham's Under-18s, six for the Under-19s and two for the Under-21s, also starting 13 of the club's first 16 fixtures in this season's Under-18 Premier League and featuring in six of Spurs' seven UEFA Youth League matches. He helped Tottenham win the Under-17 Premier League Cup in 2024-25 and has represented England at Under-18 level.
Spurs' new recruitment strategy under a "win-now" approach, which has seen the club bring in senior defensive reinforcements such as Marcos Senesi and Jan Paul van Hecke this summer, is understood to have limited Upson's pathway to regular first-team opportunities, prompting his decision to seek a fresh start elsewhere rather than remain and compete with the likes of Micky van de Ven, Kevin Danso and Cristian Romero for a place in the senior squad.
Upson's athletic profile has also drawn attention within academy circles, with the teenager previously a 100m sprint champion, a background that adds to his appeal as a modern, mobile defender. He was also selected for England's squad for the Under-17 World Cup, though injury ultimately forced him to withdraw from the tournament before it began.
The move continues a busy summer of academy recruitment for Arsenal, who have already been active in strengthening their first-team squad, and represents a rare instance of a player moving directly between the two historic north London rivals at youth level.