BBC News
Published
and as NI first minister, politicians on all sides have been reacting.
Mrs Foster, who was the first female first minister of Northern Ireland, said it had been the privilege of her life and she was now preparing to "depart the political stage".
Here are some of the reactions.
Sinn Féin
Deputy First Minster Michelle O'Neill said she had spoken to her ministerial partner earlier on Wednesday and wished her and and her family well.
"I have worked alongside Arlene Foster this past year in what has been a difficult and challenging time for everyone with the unexpected onset of the Covid pandemic," she said.