Ramsdale has become a mainstay at the Emirates since he joined the North London club from Sheffield United in 2021.
His current contract was due to expire in 2025 and, while Arsenal have not disclosed the terms of his new deal, British media reports said it was set to run until 2026, with the option to extend by a further year.
"We're all so happy that Aaron has signed a new contract," Arsenal manager Mikel Arteta told the club's website.
"The way Aaron has developed over the past two years has been exceptional, with his performances, contribution and overall adaptation to the club.
"It's great that we're continuing to build our future with our biggest talents in our young squad. We're all looking forward to enjoying many more years of Aaron the player and the person at the football club."
Ramsdale has made 39 appearances for Arsenal this season and kept 15 clean sheets in all competitions.
But the Gunners' bid to win the Premier League title has faltered in recent weeks and they are now four points behind leaders Manchester City with two games left to play.
