The BBC said Bellingham, 65, has postponed her U.K. tour of Kay Mellor's play "A Passionate Woman," which was to begin in September.
"I'm devastated not to be able to honor my commitments to the play this year," she said in a statement.
"But having toured many times before, I'm aware of the sheer stamina needed and I need to prioritize my recovery. That said, nothing's going to stop me coming back next year, and I can't wait to be 'a passionate woman.'"
The BBC said no further details about her condition or treatment have been released to the public.
Bellingham is known for her work on the TV shows "All Creatures Great and Small," "Second Thoughts" and "Loose Women." She is also the host of "Country House Sunday" on ITV.