The Minister announced her decision following a short meeting with Prime Minister Theresa May at Downing Street this afternoon.
The emergency meeting was arranged immediately after Ms Patel touched down from Nairobi from where she had been summoned earlier this morning.
Ms Patel offered her resignation after more details emerged about her private meetings in Israel, just two days after Mrs May had been assured by Patel that there was no more to come out about her meetings.
In a statement issued by Downing Street, Ms Patel said it had been a “tremendous privilege” to serve in Mrs May’s Cabinet.
“It has been a privilege to preside over a department, which has a team of remarkable individuals who often face adversity and danger in touch and challenging circumstances,” the statement said.
“Our teams across the world are displaying the ingenuity of the human spirit every single day as they strive to save lives and give vulnerable people new opportunities.
“I have seen at first hand the refugee camps and the projects we support across the world. Seeing how the aid and support provided by this country is transforming and saving lives is truly remarkable.
“These are experiences that I will never forget and will forever inform my views and outlook on the world.”
Ms Patel added: “I have seen the very best of Britain and know it will flourish on the world stage as we leave the European Union. We should all be very proud that across the world, the Union Flag on our aid parcels and on the projects we support is seen as a symbol of hope.
“Our country is a force for good in the world and as Secretary of State for International Development it has always been my focus to act in the best interest of our great country.”
The International Development Secretary was forced to cut short an official visit to Africa after being summoned by Mrs May to Downing Street to explain herself.
A Kenya Airways plane carrying the International Development Secretary touched down at Heathrow about 3:15pm amid expectations of her almost certain dismissal from the Government.
Ms Patel had been intending to spend three days in Kenya and Uganda, but was forced to cut short her trip and return home from Nairobi to explain the disclosure of further unauthorised meetings with Israeli politicians.
She has already apologised to the Prime Minister on Monday after failing to disclose a series of 12 meetings with senior Israeli figures during a family holiday in the country in August.
It has since emerged that she then held two additional meetings, one in the UK and one in the US, following her return from Israel.
In a further development, the Israeli Haaretz nwspaper reported that during her stay in the country she visited an Israeli military field hospital in the occupied Golan Heights.
Britain, like other members of the international community, has never recognised Israeli control of the area, seized from Syria in the 1967 Six-Day War.
There was no immediate comment from the Department for International Development (DfID) on the report.
Downing Street has denied a report in the Jewish Chronicle that Ms Patel told Mrs May in the lead-up to the UN General Assembly in September that her meetings in Israel had included talks with prime minister Benjamin Netanyahu.
No.10 also dismissed a claim by the newspaper that the Prime Minister had instructed Ms Patel not to include one of the latest meetings in the list she released on Monday, so as not to embarrass the Foreign Office.
“It is not true that the Prime Minister knew about the International Development Secretary’s meeting with PM Netanyahu before Friday November 3,” a No.10 spokesman said.
“It is equally untrue to say that No 10 asked DfID to remove any meetings from the list they published this week.”
International Trade Secretary Liam Fox and the rest of the delegation were reported to have continued on to their first official engagement in Uganda without Ms Patel, who has flown back to the UK.
Her return follows the disclosure that she met Israeli public security minister Gilad Erdan in Parliament on September 7, and foreign ministry official Yuval Rotem in New York on September 18.
It is understood that Downing Street was told about the New York breakfast with Mr Rotem when Ms Patel revealed the details of her trip to Israel, but No.10 only learnt yesterday about the meeting with Mr Erdan.
No British officials were present and, like her meetings in Israel, she did not report them to the Foreign Office or Government in the usual way.
She was accompanied at all the meetings bar one in Israel by the honorary president of the Conservative Friends of Israel lobbying group, Lord Polak.
Labour has already demanded an investigation by the Prime Minister’s standards adviser into Ms Patel’s meetings with the Israeli government, claiming they involved four “serious breaches” of the ministerial code.
Before the extra meetings were revealed, Downing Street insisted Mrs May continued to have confidence in Ms Patel after giving her a dressing down over her trip to Israel.
No.10 confirmed that Ms Patel had discussed the possibility of UK aid being used to support medical assistance for refugees from the Syrian civil war arriving in the Golan Heights.
However, the Prime Minister’s official spokesman was unable to say whether she had explained when she met Mrs May that the scheme would have involved supplying funding to the Israeli army.
On returning from Israel, Ms Patel commissioned work by DfID on disability, humanitarian and development partnerships between Israel and the UK.
Ms Patel only made Mrs May aware of the meetings on Friday, more than two months after they took place, when reports began to emerge of talks she held with a politician and a disability charity.
The minister apologised and admitted a “lack of precision” for suggesting last week that Foreign Secretary Boris Johnson knew about the trip, and that only two meetings had taken place.