"My relationship with Andrea Giambruno, which lasted almost 10 years, ends here," Meloni wrote on her social media accounts on Friday.
"Our paths have diverged for some time, and the time has come to acknowledge it."
The couple have a seven-year-old daughter.
Giambruno is the presenter of a news program transmitted by Mediaset, part of the MFE media group owned by the heirs of the late Silvio Berlusconi, the former premier and Meloni ally.
On two days this week, another Mediaset show broadcast off-air excerpts from Giambruno's program showing him using foul language and appearing to make advances to a female colleague.
"Why didn't I meet you before?", he tells her.
In the second, more explicit recording aired on Thursday, Giambruno is heard boasting about an affair and telling female colleagues they can work for him if they take part in group sex.
The TV journalist had already been widely criticised in August for apparent victim-blaming comments following a gang rape case.
"If you go dancing, you have every right to get drunk - there shouldn't be any kind of misunderstanding and any kind of problem - but if you avoid getting drunk and losing your senses, you might also avoid running into certain problems and coming across a wolf," he said during his program.
Meloni had said after that episode that she should not be judged for comments made by her partner, and that in future she would not answer questions about his behaviour.
