The 26-year-old underwent a medical examination in the Italian capital of Rome last night.
Joseph Alfred Duncan left the training grounds of Fiorentina on Friday morning.
He will join Cagliari on loan with an option to buy. Cagliari will cough €13 million euros to sign the midfielder permanently at the end of the season.
Duncan will link up with former coach Eusebio Di Francesco, who trained him for two seasons at Sassuolo.
Di Francesco confirmed Duncan’s imminent arrival to Italian media by saying; “I can say that he is a very welcome player."
"I hope to train him again soon," he added.
He is expected to team up with his new teammates on Monday.