Her departure comes as the broadcaster is in the middle of a major restructure of its workforce as it aims to save around £100m over the next two years.
It is not yet known if Channel 4 will replace Cochrane who has been with Channel 4 since 1998 and has worked on launches such as 4Creative and 4oD.
Cochrane has also been heavily involved this year in the development of Channel 4's strategic blueprint, Next on 4, which outlines the public service role the broadcaster plans to play in the future.
Prior to joining Channel 4, Cochrane was a member of Channel 5's launch team, overseeing its Give Me 5 campaign. She worked previously in marketing and communications at The Guardian Media Group and Conde Nast on Vanity Fair.
The broadcaster is also reducing its marketing budget in line with the cost savings plans as it looks to reduce staff numbers from 1,000 to 850.
Last week Channel 4 pulled out of the 4Digital Group as it fully abandons its plans to launch new digital radio services.
This article was first published on Marketing