Surprise move will see David Pretty replaced by the managing director of British Gas Residential Energy Mark Clare.
Pretty was appointed chief executive in 2002 after being on the company's main board of directors for 16 years. The 61-year-old will be replaced in October by Mark Clare, managing director of British Gas Residential Energy, to ensure a tidy handover.
Barratt Chairman Charles Toner said. "David was planning to retire around his 62nd birthday so we have had time to plan the succession and conduct an extensive recruitment exercise."
David Pretty spent 27 years at Barratt, 16 years as a main board director and four years as group chief executive, two years longer than he agreed on appointment.
Tonder added: "Under David's leadership the group has announced successive years of record growth in volumes and pre-tax profit. He will leave the business well placed to continue its success into the future and we wish David and his family a long, happy and well deserved retirement."