Michael Irvin: I Did NOT Have Sex with Accuser ... Period.

Michael Irvin says he did NOT have any sort of sexual relations with the person accusing him of sexual assault ... telling TMZ Sports he treated the woman like family in the years before the incident.

Irvin appeared on the "TMZ Sports" TV show (airs tonight on FS1) and said he's NEVER had any sort of sexual relationship with his accuser ... including on the night in question.

"She was like my niece ... a good friend," Irvin said. "I was hurt to hear about [the allegation]."

As we previously reported, Irvin is being investigated for allegedly sexually assaulting a 27-year-old woman in his Florida hotel room on March 21. Irvin says he believes video evidence will prove his innocence.