Arsenal's official statement read: "Karl Hein will complete a permanent move to Bundesliga side Werder Bremen in July 2026. We thank Karl for his contribution to the club during his time with us and wish him all the best for his next chapter with Werder Bremen."
Hein, 24, joined Arsenal from Estonian club Nomme United in June 2018 and made his senior debut in November 2022 in a Carabao Cup tie against Brighton & Hove Albion. He spent last season on loan at Real Valladolid, making 32 appearances, before joining Werder on loan this summer.
His playing time in Germany was limited to two Bundesliga appearances, but Werder activated a €3 million purchase option in his loan agreement to make the move permanent. Sky Germany journalist Florian Plettenberg confirmed the deal, with transfer specialist Dominik Schneider reporting that Hein will sign a four-year contract running until June 2030.
Werder confirmed Hein is expected to become their new first-choice goalkeeper following the impending departure of Mio Backhaus. The 22-year-old Backhaus has an agreement in place with SC Freiburg, with negotiations over a transfer fee ongoing. Reports in Germany have suggested a price of around €15 million for Backhaus.
Hein is an Estonia international with 45 senior caps for his country. Arsenal will receive a modest return of around £2.6 million from a player who joined as a teenager and never forced his way into first-team contention at the Emirates Stadium.