Arsenal have confirmed that Semi Ajayi has joined the club after impressing during a trial period.
Ajayi blew the lid on the proposed move last week after tweeting that he had signed a contract with the Gunners.
No official announcement was forthcoming but now speculation has been put to bed after the official website confirmed he has joined the club.
The 19-year-old played in the under-21 game against Blackburn Rovers and impressed, scoring a goal as Arsenal's young guns romped to 3-0 win.
Centre-back Ajayi then put in another solid performance in a 1-0 win against West Brom at the Emirates stadium in September.
Ajayi has represented Nigeria at under-20 level three times but is still eligible to play for England, having been born in London.
At 6ft 3in, Ajayi cuts the figure of an imposing centre-back and, after coming through the ranks at Charlton, will help to add steel to Arsenal's under-21 side.
The Arsenal website stated: "Everyone at Arsenal would like to welcome Semi to the Club."