The Spanish club has confirmed that Real Sociedad have signed a two-year deal with Premier League side Australia goalkeeper Matt Ryan and Brighton & Hove Albion.
After four years at Brighton, 29-year-old Ryan returned to La Liga, a three-year stint at Valencia from 2015–17.
Real Sociedad said Ryan's deal includes an option for a one-year extension.
"I will work hard and I can't wait to start playing for the team," Ryan, who capped 61 times for Australia, said in a media release.
Ryan had one season remaining on his contract with Brighton.
He was loaned to Arsenal in the middle of last season after losing his place to Brighton keeper Robert Sanchez.
A veteran of two World Cups, Ryan helped Australia to an eighth consecutive win in Asian qualifying for the 2022 tournament in Qatar with a clean sheet in a 1-0 win over Jordan last month.