Wojciech Szczęsny has completed his shock move to Barcelona to help manage the Catalan club's goalkeeper crisis after Marc-André ter Stegen's long-term injury.
"FC Barcelona and Wojciech Szczęsny have reached an agreement for the goalkeeper to join the Club until 30 June 2025," the club statement said.
"The Polish keeper comes to the Club in unusual circumstances but there is no doubt that his CV speaks for itself.
"During his career, which appeared to have come to an end in the summer, he has played at top clubs such as Arsenal, Roma and Juventus since leaving his home town of Warsaw at the age of 16."
Szczęsny, 34, retired from football after the European Championship but told Diario Sport last Wednesday that he would consider a move to Barça, given the size of the club and its history.
ESPN previously revealed that Barça would look to sign a free agent to compete with backup goalkeeper Iñaki Peña after Ter Stegen ruptured a tendon in his knee.
Former Poland international Szczęsny looked to have finished his club career with Juventus, having previously played for Arsenal in the Premier League and at Roma on loan.
Peña, who made 17 first-team appearances last term when Ter Stegen was out with a back problem, replaced the Germany international when he went off against Villarreal.
The 25-year-old kept the gloves for Wednesday's 1-0 LaLiga win against Getafe at the Olympic Stadium and the 4-2 defeat to Osasuna on Saturday ahead of Barça's Champions League clash with Young Boys on Tuesday.