Amber Rudd resigned as Home Secretary on Sunday night.
Downing Street issued a statement around 10pm saying Prime Minister Theresa May had accepted her resignation.
The Conservative MP decided to quit after it emerged she wrote a letter in January 2017 setting out an “ambitious but deliverable” increase in enforced deportation from the UK.
On Friday, she had said she had been unaware of targets for deportations.
Rudd had come under pressure to quit since details of the Windrush scandal first emerged.
Migrants from Caribbean countries who arrived in the UK after the second world war were declared illegal immigrants.
Many of the Windrush generation have had benefits cuts or lost, been refused jobs or threatened with deportation.
Some were event refused medical treatment.