The 30-year-old, who left the club for Inter in 2008, makes his comeback at the Estadio do Dragao after a spell as a free agent.
As well as Inter, Quaresma had stints at Chelsea, Besiktas and the Dubai-based Al Ahli after leaving Portugal, but insists Porto is where he feels most at home.
"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."
Porto currently sit tied on 33 points with both Sporting Lisbon and Benfica at the top of the Primeira Liga.
