Conn’s departure was agreed last summer after a slump into deep losses and a dividend cut proved the final straw with the company having lost around two thirds of its value under his leadership.
Centrica announced on Tuesday that Charles Berry has stepped down as chairman of the former energy monopoly under advice from his doctor and has been replaced in the role by Scott Wheway.
The first action by Wheway, a former boss of Boots and Best Buy, was to give Conn the final push.
Chief financial officer Chris O’Shea will take over from Conn on a temporary basis.
"I'm acutely aware that I'm taking this role at a time when we need to navigate our way through the current volatility caused by the impact of Coronavirus,” Wheway said.
“As a business we remain focussed on structural simplification, improving our efficiency and delivering growth in our customer facing businesses.
“I will immediately be concentrating on completing the search for a CEO for Centrica, which includes both internal and external candidates.”