Daniel Cook, currently director of strategy and planning at RICS, will move to the LI next month.
Denton-Thompson said: ‘We are excited to have secured Daniel for this important role. He is an energetic leader and thought leader with an excellent track record of turning insight into strategy.
"He understands the changing dynamics impacting on professional membership organisations operating across both the natural and built environment.
"He also has a wealth of experience and knowledge spanning earth science, urban planning, policy and politics, as well as a great network that will be of great benefit to the future development of the landscape profession."
Denton-Thompson said that Cook will join at an exciting time for the institute, which is modernising its governance and broadening its membership, both in the UK and abroad.
Cook will also seek to improve engagement with the next generation of landscape professionals and progress the LI’s focus on education.
He said the LI was an organisation at the forefront of placemaking.
"The work of landscape professionals is inspirational and makes a real difference to us all. There are great opportunities across a range of disciplines including land management, well-being, resilience and green infrastructure.
"My approach will be to boost engagement and collaborate even more with partner organisations in the landscape fields and beyond. I also take seriously the public interest remit to which chartered bodies must adhere.
"To be successful we will need to be open to innovation and re-invention. Our job is to lead, to share, to be flexible and inclusive to remain relevant and to ensure trust in professions against a backdrop of major change."
During his eight years at the RICS, Cook has led market insight, helped to develop its first corporate strategy, pushed international expansion and led on the RICS Futures programme.
Cook replaces Phil Mulligan who has left due to family commitments. Mulligan became chief executive in November 2013 after a period as interim chief executive.