The former Barcelona, Inter and Chelsea man has returned to his native country as he aims to get his career back on track.
Ricardo Quaresma has voiced his delight at his return to Porto and says he is determined to help the reigning champion to more glory.
The 30-year-old, who left the club for Inter in 2008, makes his comeback at the Estadio do Dragao after leaving Al Ahli in the summer of 2013.
"I'm happy to be back to a home I know quite well, where I feel the love and the trust of those around me," he told the club's official website. "It's important to be happy and this is the place for that. I am prepared to help the team, the club and the fans in winning more titles.
"I am extremely proud to be back and I recovered my joy in playing football. When I'm happy, I fear nothing."
Quaresma, who scored 24 goals in 114 league appearances in his first spell at the club, reserved special thanks for chairman Jorge Nuno Pinto da Costa and coach Paulo Fonseca.
"I really am proud to wear this jersey again and I'd like to thank these two men in particular, for believing in me and in my value."
Quaresma started his professional career with Sporting CP and also wore the jerseys of Barcelona, Inter, Chelsea and Besiktas before joining Al Ahli one year ago.