The move ends a recruitment process launched in January after Per Mertesacker confirmed he would leave the role at the end of the season.
Mertesacker had overseen Arsenal's youth ranks since 2018, moving straight into the job after retiring as a player.
Myles Lewis-Skelly, Ethan Nwaneri and Max Dowman are among the graduates of Arsenal's Hale End academy to break into Mikel Arteta's first team during Mertesacker's tenure.
De Maesschalck arrives with a strong track record in youth development across European football.
He spent three years as director of youth development at Monaco, following a highly successful ten-year spell as head of academy at Club Brugge in Belgium.
Arsenal confirmed De Maesschalck will officially join the club on 1 August, moving from French side Strasbourg, where he has served as technical director since 2024.
"We are delighted to announce the appointment of Pascal De Maesschalck as our new academy director," the club said in a statement.
"Pascal will officially join the club on August 1 from French club Strasbourg, where he has served as technical director since 2024," the statement added.
Arsenal outlined De Maesschalck's remit going forward.
"As our academy director, Pascal will lead our academy programme, overseeing the development of our young players while helping to further strengthen our recruitment of outstanding young talent from across the UK and around the world," the club said.
"His appointment reflects our continued commitment to building one of the world's leading academies and ensuring talented young players have the environment, support and opportunities to reach their full potential," the statement continued.
Arsenal sporting director Andrea Berta welcomed the appointment.
"We are delighted to welcome Pascal to Arsenal. He brings extensive experience from some of Europe's leading football clubs and has an outstanding track record in youth development," Berta said.
"We are excited to have him with us as we continue to build for the future, developing young players and identifying the best emerging talent to join Arsenal on a journey towards professional football," Berta added.
De Maesschalck now takes on the task of keeping Hale End's conveyor belt of talent running for years to come.