Jay Hunt, Channel 4's chief creative officer and the force behind it securing the Great British Bake Off, is leaving the broadcaster.
She will step down from her post at the end of September after almost seven years in the role.
Hunt's decision came days before Channel 4 is expected to announce its new chief executive, succeeding David Abraham who is stepping down as boss of the broadcaster.
Hunt, who has been instrumental in bringing the likes of Gogglebox, First Dates, Humans, The Island With Bear Grylls and the Paralympics to the channel, was said to be a favourite for the role.
"I've loved being at Channel 4 and am incredibly proud of how far we have come creatively. From the multiple Channel of the Year awards to the raft of global hits, we've had real success," she said.
Hunt, who brought BBC gem Bake Off to Channel 4, added: "I will continue in post till the end of September and am looking forward to Channel 4 delivering not just an exciting summer of sport but the richest autumn schedule we've ever had with big shows from the Great British Bake Off to Electric Dreams...
"Channel 4 is a unique and special place. I've really enjoyed leading this phase of its creative renewal and I'll be cheering the new leadership team on from afar."
Channel 4 chief executive Abraham said of the former BBC1 controller: "Jay took on one of the biggest challenges in broadcasting back in 2011 and through immense creativity, courage and determination has delivered magnificently.
"In recent years the delivery of our remit and our creative output has reached new heights and both I, the staff of Channel 4 and the whole industry owe Jay huge thanks for all she has achieved."
The Conservatives have pledged to relocate Channel 4 out of London, but ensure the broadcaster remains publicly owned, if they win the General Election.