Russell Brand is now facing rape and sexual assault charges for 4 separate alleged incidents, dating as far back as 1999.

The comedian was hit with with one count of rape, one count of indecent assault, one count of oral rape and 2 counts of sexual assault ...  this according to London's Metropolitan Police Service.

Detectives began investigating the comedian after a series of allegations were made against him in 2023 ... and, they now allege Brand committed a series of assaults between 1999 and 2005.

We spoke with law enforcement ... and they tell us Brand is not in police custody at this time, but is expected to be in court May 2 to face the charges.

Brand vehemently denied the claims of rape against him back in 2023 just before Channel 4's Dispatches and The Sunday Times released a joint report of multiple women claiming Brand abused them between 2006 and 2013. He insisted all of his sexual activity over the years has been consensual.

A couple months after the report came out, Brand was sued by a woman claiming he sexually assaulted her on the "Arthur" movie set ... another claim he denied.

Brand has admitted to drug and alcohol abuse in his past ... though he's documented his life changes in more recent years, including his baptism in April 2024.

We've reached out to Brand ... so far, no word back.