18-year-old England U19 international moves for fee of just under £1m; Gunners saw Setford as potential Ajax No 1 and he will regularly train with first team this season
The 18-year-old joins the Gunners for a fee just under £1m after entering the final year of his contract with the Dutch club, where he was a member of their U21 side.
Setford was born in the Netherlands but has already represented England at U17 and U19 level, most recently in the latter's 1-1 draw with Morocco in March.
He will join the Arsenal on their pre-season tour of America, which leaves on Sunday and includes friendlies with Bournemouth, Man Utd and Liverpool. Arsenal believe Setford was potentially on course to become an Ajax No 1 in future, and plan to include him regularly in first-team training in the coming season.