Roberts came out in a Sunday Facebook post in which she reflected on the past year, thanking her loved ones -- including her "long time girlfriend, Amber" -- for supporting her during her battle with myelodysplastic syndrome.
"I am grateful for my entire family, my long time girlfriend, Amber, and friends as we prepare to celebrate a glorious new year together," Roberts wrote.
The First Lady said she is "so happy" for Roberts and her girlfriend, who "continue to make us all proud."
See Obama's tweet below:
Read Roberts' full Facebook post below: