The 39-year-old actress wed IT boss James in a traditional church ceremony in October 2012. However, in a chat with Britain's Daily Mail newspaper, Joanne revealed that she and her spouse have now gone their separate ways.
"We've actually been separated for a little while," she told the publication when asked about her other half. "I'm looking to the future."
She also said that being single hasn't put a stop to her dreams of becoming a mother at some point, adding, "If it happens, it happens. And if it doesn't, I hope I'll still feel I can live a happy and fulfilled life."
Joanne and James set up production company Run It together, and are said to be planning to continue working together despite no longer being romantically involved.
Joanne is most famous for playing housemaid Anna Bates in the period drama and spinoff movie, and has also starred in programmes such as "The Commons" and the critically-acclaimed "Liar", which is returning for its second season in the U.K. later this year 2020.