"I've gone back," she told a radio show shortly after AN leader Gianfranco Fini, who was being interviewed on the programme, said the row had been resolved. "He didn't want to lose me and I didn't want to lose him."
Mr Fini told state radio RAI that he met Ms Mussolini thanks to the good offices of Giuseppe Tatarella, AN's leader in the Chamber of Deputies (lower house), and they had overcome their differences.
Ms Mussolini, 33, resigned from the parliamentary party group for what she said were strictly political reasons. The fiery politician, who is also a niece of the film star Sophia Loren, had accused AN leaders of stifling internal party debate.
Ms Mussolini, who sits in the Chamber, told La Stampa newspaper last month after quitting AN's parliamentary party that she was considering joining the neo-fascist Social Movement (MS-Fiamma) formed by some of her father's followers in the Second World War.