The new prime minister Theresa May has carved up the Cabinet bringing in a host of new faces onto the frontbench.
Ms Greening moves into the Department for Education from the Department for International Development.
The MP for Putney, Roehampton and Southfields has been a major advocate for girls’ education in her role as international development secretary.
Last month, she staged a Girls’ Education Forum in a bid to bring global attention to the issue of girls’ education.
Ms Greening is believed to be the first education secretary to have attended a comprehensive school, Oakwood Comprehensive in Rotherham.
Kevin Courtney, acting general secretary of the NUT, responded to her appointment by calling for her to look at recruitment and retention".
“We congratulate Justine Greening on her appointment as the new Secretary of State for Education. We want to engage with her, representing the views of the profession and seeking positive change for our young people," Mr Courtney said.
"There are real problems to be addressed: teacher recruitment and retention, mainly caused by excessive working hours is at crisis point; a lack of school funding is jeopardising the quality of education; and testing and assessment is in complete disarray.”
Malcolm Trobe, interim general secretary of ASCL, echoed the NUT's concerns about recruitment.
"Urgent action is essential to address severe teacher shortages which are making it increasingly difficult to maintain standards or raise them further," he said. "The worst-affected subjects are maths, sciences and English, the very subjects which are most important to the life chances of young people. This cannot go on. Schools and colleges are doing a fantastic job under increasingly difficult circumstances but they must have sufficient funding and teachers.”
In a tweet Ms Greening said she was "delighted" to have been appointed as education secretary.