Arsenal have completed the signing of Brazilian defender Gabriel Magalhaes from Lille for 26m euros (£23.14m).
The 22-year-old, a left-footed centre back, made 34 appearances in all competitions for Lille last season as they finished fourth in Ligue 1.
He joins the Gunners on a long-term contract.
"He is a player we have been studying for a while and he was in demand from many clubs," said Arsenal technical director Edu.
"Gabriel is a player of high quality and Mikel (Arteta) and his coaches are looking forward to integrating him into the club."
Arsenal boss Mikel Arteta said: "We welcome Gabriel to Arsenal. He has many qualities which will make us stronger as a defensive unit and as a team.
"He has proved with Lille he is a defender with many outstanding attributes and we are looking forward to watching him grow as an Arsenal player."
Gabriel said he considered offers from a number of clubs before deciding to join Arsenal.
"It was a very surreal experience, there were offers coming from a few different clubs," he said.
"I spoke a lot with my family and my agents, I also spoke with some of Lille's directors but, as I said, this club's history and traditions and the team project for the next few years were very motivational for my decision to come here.
"So here I am, wearing the Arsenal shirt - I will give my best for it."