The former FC Barcelona star will be unveiled at a special event in Miami on June 23, although it remains unclear whether the 46-year-old will actually feature for Ravenna during the upcoming season.
Ronaldinho confirmed his return with an emotional message to supporters, promising to bring back the joy and creativity that made him one of football's most entertaining players.
"New colours, same smile," Ronaldinho said.
"I can't wait to be able to dance on the ball again and write a new story together with Ignazio and the whole Cipriani family. Football has always been a source of joy for me, and I want to bring the same spirit to Ravenna."
Ronaldinho last played professionally for Fluminense FC in 2015 before stepping away from the game. During his career, he won major honours including the FIFA World Cup with Brazil in 2002 and the UEFA Champions League with Barcelona.
Ravenna owner Ignazio Cipriani said bringing Ronaldinho to the club was a dream moment, admitting the midfielder was a huge influence during his childhood.
"He was my idol growing up, and his impact on the game extends far beyond football," Cipriani said.
"Beyond what he brings to the club, I hope his involvement inspires a new generation of supporters to fall in love with Ravenna FC and become part of what we're building for the future."
Ronaldinho will now join a special group of former Italian internationals who have represented Ravenna, including Christian Vieri, Fabio Cannavaro, Alberto Gilardino and Vincenzo Montella.