Arsenal have announced the signing of 19-year-old Finland Under-21 defender Carl Jenkinson from Charlton.
The 6ft 1in right-footer, who also qualifies to play for England, made his debut for the Addicks in December 2010 and featured eight times last season.
He was predominantly deployed at full-back but can also play at centre-back.
"I hope supporters will understand why I can't turn down such an opportunity, but Charlton will always have a place in my heart," said Jenkinson.
"I will always be in Charlton's debt for the training they have given me since a young age.
"I'm grateful to the club's academy and all the coaching staff, so I'm delighted the two clubs have come to an agreement."
Jenkinson, whose transfer fee has not been disclosed by either club, is the Gunners' first summer acquisition following their sixth successive season without a trophy.
He was born in England to a Finnish mother and has already represented both countries at youth level, captaining Finland Under-19 side earlier this year.
Charlton chief executive Stephen Kavanagh stated: "This is a great move for Carl, and it's difficult to stand in the way of a player when a club the size of Arsenal expresses interest, particularly if, like Carl, you come from an Arsenal-supporting family.
"The last few weeks of the season were difficult as the deal was finalised but could not be signed until the Premier League transfer window opened.
"But Carl's attitude throughout has been exemplary, and he made clear from the start that he wanted the club that produced and nurtured him to benefit from the deal in the right way and not by having to rely on compensation rights.
"I would like to thank Carl, his father and Arsenal for their professional manner in dealing with matters."
Jenkinson, a boyhood Arsenal fan, also attracted praise from Addicks boss Chris Powell for the way in which he had conducted himself and for his potential on the pitch.
"I want to put on record how much I admire Carl as a player and, more importantly, as a young man," said Powell.
"I wish him well on behalf of all the staff and players because it's a dream move for him.
"If he grows into the right-back we all feel he could be, we could be talking about a player playing at the highest level for a long time."
Arsenal have also tied England youngsters Benik Afobe and Chuks Aneke to long-term deals, along with Dutch youth international midfielder Oguzhan Ozyakup.