Jurrien Timber made his debut for Ajax in March 2020Arsenal have completed the signing of Netherlands defender Jurrien Timber from Ajax for £34m.
Timber's fee could rise to £38.5m and the 22-year-old joins on a long-term deal.
He will further bolster Arsenal's defence after centre-back William Saliba agreed a new four-year contract.
"We're really excited Jurrien has joined us. He is a versatile young defender," said Arsenal manager Mikel Arteta.
"Jurrien is a young player, but has already achieved so much. He has experienced what it's like to go to a major international tournament on more than one occasion, as well as the trophies he has won with Ajax. We look forward to welcoming and integrating Jurrien into the squad."
The versatile Dutch defender, who can play in the centre of defence or at right-back, had been linked with Manchester United, while Bayern Munich were also known to be interested.
Timber has 15 caps for the Netherlands, including four at the Qatar World Cup, where he helped Louis van Gaal's side reach the quarter-finals.
He will add strength to the spine of an Arsenal team that finished runners-up to Manchester City in a closely fought Premier League title race last season and qualified for the Champions League after a six-year absence.
His signing follows that of 24-year-old Germany forward Kai Havertz from Chelsea, with West Ham midfielder Declan Rice also close to completing a club-record £105m move to the Emirates Stadium.
Arsenal have also agreed new contracts with Bukayo Saka, 21, and Reiss Nelson, 23, while experienced Switzerland midfielder Granit Xhaka, 30, joined German side Bayer Leverkusen for 25m euros (£21.4m).
Timber made 47 appearances in all competitions for Ajax last season, including all six of their games in the Champions League group stage, and helped the Amsterdam side to win the Eredivisie title in 2021 and 2022.
Arsenal sporting director Edu said: "We are very happy to bring Jurrien to Arsenal. He is a player that we have admired for a long time, so it's a credit to everyone in our team that made this happen."
"Jurrien is a young, talented international player, who fits our vision of competing with a young strong squad. I know Jurrien cannot wait to get started and we're really hoping that he will be a great success here for many years."
