Meslier made 215 appearances across seven seasons with the Yorkshire club, keeping 70 clean sheets. BBC Sport was first to reveal Arsenal's interest in the 26-year-old on 30 June, and the transfer has now been completed after Meslier lost his place as Leeds' number one and became available on a free transfer at the end of his contract.
"I'm very happy and very proud to join Arsenal," the French goalkeeper said.
"I cannot wait to show the love that I've got for this badge, and I cannot wait to win trophies with this team, because this is a club that needs to lift trophies again and again."
He added that he "cannot wait to win trophies" with "the biggest club in England."
Arsenal's first-choice goalkeeper David Raya won the Premier League Golden Glove in 2025-26 for the most clean sheets, with 19 in 37 games, as the club won the title. There is a doubt over current second-choice Kepa Arrizabalaga's future heading into next season, which prompted Arsenal to explore the market for a replacement.
Meslier arrives as third-choice goalkeeper behind Raya and Arrizabalaga, but could be promoted into the number two role if Arrizabalaga departs as expected. His arrival is likely to mean 20-year-old goalkeeper Tommy Setford leaves on loan this summer to continue his development elsewhere.
Meslier's departure ends a seven-season association with Leeds that began when he arrived on loan from Lorient in 2019, before the move became permanent the following year. He was a near-ever-present for the Yorkshire club during their promotion campaigns and their subsequent spells in the Premier League, establishing himself as one of the division's most reliable shot-stoppers at a young age before a dip in form and the emergence of alternative options saw him lose his place last season. Leeds have since signed a replacement and are also exploring the market for further additions between the posts as they prepare for the new campaign.
For Arsenal, the deal represents a low-cost way of adding proven Premier League experience to their goalkeeping options without disrupting the pecking order established by Raya's title-winning campaign. Manager Mikel Arteta is understood to have sanctioned the move as part of a broader effort to strengthen squad depth across several positions this summer.