Ashley Darby is closing the book on her marriage to Michael ... because their divorce is now official ... TMZ has learned.

The "Real Housewives of Potomac" star's divorce became a done deal Monday, according to online court records.

Ashley filed for divorce in November -- a little more than 2 years after they separated -- and as we first reported, they had a prenup.

Michael previously told us their agreed settlement included sharing custody of their two sons, Dean and Dylan ... and he said the settlement was "amicable and fair."

Ashley announced her split from Michael back in April 2022 ... explaining she and her businessman husband of nearly 8 years had decided to separate since they were in "very different stages in our lives."

The pending divorce was a hot-button topic on 'RHOP' for several seasons until Ashley finally followed through and filed the paperwork.

Now, she's going to need some new storylines ... and it will be interesting to see how she navigates being a single mom.