The 31-year-old has trained with the Brazilian club since December and was officially added to Atletico's squad on Tuesday, reported media. (Agencies)
"It's very gratifying, especially after so much hard work and dedication during the period that I've trained with the team," Adriano told the club's official website.
"I'm getting an opportunity to return to football with Atletico."
Adriano has not played since March 2012 after suffering a recurrence of an Achilles tendon injury that required surgery for a second time in two years.
During that time he has been sacked by both Corinthians and Flamengo due to disciplinary reasons.
Looking lean and showing renewed enthusiasm, Adriano said he was keen to lead Atletico Paranaense to their first Copa Libertadores title, South America's most prized club trophy.
"The Copa Libertadores is the only title that I haven't won and I want to help Atletico win it," the former Inter Milan, Parma and Roma forward said.
"I want to gain more rhythm and fight my way into a starting position. I will continue working hard to get into the game and do what I know best, which is scoring goals. I want to help Atletico win titles and make the fans happy."
Adriano was once considered one of the most potent strikers in world football.
He has scored 27 goals from 48 matches for Brazil and won the Golden Ball award for the best player at both the 2004 Copa America and 2005 Confederations Cup, in which he also top-scored.
The 31-year-old has trained with the Brazilian club since December and was officially added to Atletico's squad on Tuesday, reported media.