Gavin Patterson will stand down as the chief executive of BT by the end of the end of 2018 after five years in charge.
Patterson said 15 months ago that BT had been taken aback by the flak it had received about the company's customer service and its networks, and he vowed that its millions of customers would see improvements.
The telecoms giant said it has launched a search for his replacement and expects to have a successor in place during the second half of the year.
Jan du Plessis, chairman of BT, thanked Patterson for his contribution but said the company needed a change in leadership.More news: Actor Vince Vaughn arrested for DUI, resisting arrest
"The broader reaction to our recent results announcement has, though, demonstrated to Gavin and me that there is a need for a change of leadership to deliver this strategy".
Mr Patterson has been at BT for 14 years, 10 of those as a board member.
This included job cuts and organisational changes that aimed to let BT to lead the market in 5G and converged networks, but BT's share price dropped to a six year low.
Days later, the company revealed Patterson was paid £2.3 million (€2.6m) a year ago, including a £1.3 million bonus.More news: Anthony Bourdain dead: French prosecutor confirms ‘no evidence of foul play’
"The rise of BT's Sport coverage, which has stepped up to challenge the dominance of Sky initially brought some good times for investors".
But the victories were eclipsed by problems, led by a fraud had left a 530-million pound black hole in its Italian business.
Patterson was also embroiled in fractious talks with Britain's telecoms regulator Ofcom about the fate of Openreach, which runs the national broadband network.
He will continue in his role until the new boss is named.More news: Verizon names tech chief CEO, prioritizes 5G network over content
"I am confident that, for the remainder of his term, Gavin and his senior management team will continue to display the energy required to deal with every dimension of the task at hand", he said.