Last week Honda announced that it had agreed to part ways with the eight-time world champion mutually at the end of the season, despite Marquez being contracted for next year.
Marquez, who won all six of his premier class titles with Honda having spent the last 11 years with the Japanese marque, has been heavily linked to Gresini for some time.
Honda’s efforts to retain Marquez, which included a recruitment drive to snare European engineering talent to help improve its bike, ultimately came to nothing.
HRC’s announcement all but paved the way for Marquez’s Gresini switch, though the Ducati satellite squad remained silent until Thursday when it formally confirmed the Spaniard’s appointment.
“This is a historical moment for the Gresini Family," team boss Nadia Padovani said.
"The fact that Marc Marquez chose to race with us in the upcoming season is absolutely fantastic and I’m extremely happy to be able to make it official.
"In less than a season we got really close to his brother, and we’ll welcome Marc the same way, as we’re sure he has all the potential to be competitive on the GP23 from the get-go.
"Last but not least, I would like to thank Fabio Di Giannantonio for his professionalism, and we wish him all the best for the continuation of his career.”
Source: Autosport