The 28-year-old, who joined Fiorentina from Bayern Munich for a reported 20million euros last summer, damaged ligaments in his right knee during a match against Cagliari in September.
The Germany international was expected to make a comeback in December but his return was postponed due to swelling in the surgically-repaired knee.
However, he is now closing in on a return to action, with a statement from Fiorentina saying: "Mario Gomez has started his gradual return to the group with a lot of will, plenty of smiles and a spectacular acrobatic goal."
Gomez is expected to sit out Saturday's match against Atalanta and next week's Coppa Italia semi-final second leg against Udinese but could feature in Fiorentina's home game against Inter Milan on February 15.
"We cannot forget that he (Gomez) has been out of action for five months and we cannot rush his comeback," Fiorentina coach Vincenzo Montella said to www.acffiorentina.it.
Fiorentina are still without the team's top scorer Giuseppe Rossi, who is sidelined with a knee injury until April.