Roberts, a 51-year-old breast cancer survivor, is undergoing the procedure to treat a rare blood disorder.
Roberts bid farewell on Twitter Monday morning.
"My last tweet for awhile. Heading to hospital...time to focus on healing. I take each & every one of you w/me in my heart. Light and love," Roberts wrote.
Roberts had left Good Morning America on medical leave in August, then traveled to Mississippi to see her ailing mother Lucimarian Tolliver Roberts, who died shortly after she arrived.