Alison Carnwath has been in role since 2008
Developer Landsec said it has begun the search for a new chairman to replace Alison Carnwath who is stepping down from the role later this year after nine years in the position.
Carnwath has been on the board since September 2004 when she joined the firm as a non-exec.
She became chairman in November 2008.
The Walkie Talkie developer said Carnwath, who worked in investment banking and corporate finance for 20 years, will continue to work at the firm until a successor is appointed. She was appointed a dame in 2014 for services to business.