Ian Livingston said: 'I am honoured to have been asked by the Prime Minister to take on the role of Minister for Trade and Investment, with a remit of helping the growth of British companies and the country's future economic success.
"It has been an incredibly hard decision to leave BT at such an exciting time. However, the opportunities ahead and the strength of the management team that Gavin will lead mean that the company is in a great position.
"I am immensely proud to have led this company over the last five years. We have made huge progress over the last few years but I know there is still so much more that BT can and will do."
Ian will join the House of Lords prior to taking up his front-bench government post in December.
An announcement about the specific September date on which Ian will hand over the BT chief executive's post to Gavin will follow in due course.
Biography of Gavin Patterson
, 45, became Chief Executive of BT Retail in
and joined the BT Group plc board a month later. He will succeed
as chief executive of BT Group in September.
Gavin joined BT in
as managing director of its consumer division. He previously spent four years at Telewest (which later merged with NTL to become Virgin Media), including as managing director of its consumer division. Before entering the communications sector, he spent nine years at Procter and Gamble, rising to become European marketing director.
As well as leading BT's retail division, Gavin oversees corporate responsibility programmes for BT Group and represents the company on the CBI's Climate Change Board. He has served as President of the Advertising Association since
, is a non-executive director of British Airways and a Trustee of the British Museum. He also sits on the advisory board of the
Judge Business School.
Gavin graduated from
with a degree in chemical engineering and is married with four children.
BT is one of the world's leading providers of communications services and solutions, serving customers in more than 170 countries. Its principal activities include the provision of networked IT services globally; local, national and international telecommunications services to its customers for use at home, at work and on the move; broadband and internet products and services and converged fixed/mobile products and services. BT consists principally of four lines of business: BT Global Services, BT Retail, BT Wholesale and Openreach.