Greening was the youngest female Conservative MP in the House of Commons[8] until Chloe Smith was elected to Parliament on 12 October 2009.

[12] Subsequently, Sir Philip Rutnam, then Permanent Secretary at the Department for Transport, issued an apology to Greening stating the problem "clearly the responsibility of officials and not ministers".

[13] A report by the Transport Select Committee found fault with Greening and revealed that the cost to the taxpayer of the flawed franchise process was at least £40 million.

[15] The move was strongly criticised by the Mayor of London Boris Johnson who believed it was linked to her opposition to a third runway at Heathrow.

[17][18] Greening led the UK response to international natural disasters such as Typhoon Haiyan in the Philippines in 2013[19][20] and the Nepal earthquake in 2015.

[21][22] In 2014, Greening held the first-ever Girl Summit in London, which saw leaders and young people from all over the world come together to work to help combat female genital mutilation and early and forced marriage.

Greening pioneered the "No Lost Generation" initiative with then UNHCR boss Antonio Guterres and UNICEF to enable Syrian refugee children to still continue their education.

[25] Greening led the international response to the Ebola outbreak in Sierra Leone in 2014–2015, committing a £230 million aid package including support for 700 treatment beds and funding for children orphaned by the crisis.

[29] Following an initiative by Greening, Ban Ki Moon, then UN Secretary General, announced in 2016 the creation of the UN's first high-level panel on women's economic empowerment.

[32] Greening further pressured UK businesses and other countries to "put their hands in their pockets"[33] to help before warning the European migrant crisis could last 20 years if nothing was done.

[35][36] Greening was appointed Secretary of State for Education[37] and Minister for Women and Equalities by Theresa May on 14 July 2016, replacing Nicky Morgan in both roles.

[40][41] In the June 2017 general election, after which the Conservatives formed a minority government, she held her Putney constituency with a reduced majority and a loss in vote share of 9.7%.

Later that year, she became the first senior Conservative to come out in favour of a new EU referendum, arguing that Parliament was unable to make a decision on Brexit and therefore it had to be put back to the people.

Greening said: "Well, things need to change, don't they, and people need to have some hope for the future that Britain can be a country that runs differently and more fairly."

[56] In 2020, following the outbreak of the COVID-19 virus and ensuing United Kingdom lockdown, she campaigned for businesses to provide extra support to their employees, customers and communities during the crisis.

"[60] Greening was previously in a relationship with Mark Clarke, a former Conservative parliamentary candidate for Tooting who was expelled from the party for his involvement in a bullying scandal of young members.