The "Good Morning America" co-anchor sent a video message taped from her New York hospital bed for airing on the program Thursday, which is the day she's set to have the transplant.
Declaring that "thoughts are so powerful," Roberts told her audience: "I feel the love and I thank you for it."
Roberts' transplant comes after 11 days spent in the hospital and eight days of chemotherapy to prepare her for the procedure. The donor is her older sister, Sally-Ann Roberts.
In June, the 51-year-old Roberts disclosed that she has MDS, a rare blood disorder.
Her last day on "GMA" was Aug. 30 before she began extended medical leave from the ABC morning show.