Fiona Reynolds is to leave the National Trust after more than 11 years as director-general.
Reynolds, 53, will become Master of Emmanuel College at the University of Cambridge in the autumn of 2013 and will stay in her post at the trust until a successor is in place.
She plans to use the time before starting at Cambridge to write a book about her years at the trust.
Under Reynolds’ leadership, trust membership increased from 2.7 million in 2001 to four million last year. Visitors to the trust’s 300 properties grew from 10 million to 19 million in the same period. The trust is the country's largest membership charity.
Recently, Reynolds has been at the forefront of a campaign against proposed changes to the planning laws.
More than 100,000 people signed the trust's petition, and there were angry reactions from ministers, especially the planning minister, Greg Clark.
Of her time at the trust, Reynolds said: "I am incredibly proud of all that we have achieved in the past 11 years. There is no organisation like it and I will miss it terribly. But it is time to allow someone else an opportunity to make their mark."
She is the first woman to be elected Master of Emmanuel College.