O’Brien was hired by former CEO James Warburton in June 2011 following the resignation of Mike Morrison after less than six months. He will finish on July 31.
National Sales Director, Louise Barrett, will now run TEN’s Sales department.
“Working at Network TEN has been an amazing experience. I’ve worked with some great people here and we have a great team, including Louise Barrett, Kylie Rogers, Rod Prosser, Sarah Keith and others. I’ve achieved what I set out to do at Network Ten and the time is right to hand the reins to the next generation of executives,” O’Brien said.
TEN CEO Hamish McLennan, said: “We are very sorry to see Barry go, but we understand his desire to step back from his current role and look for new opportunities.
“We are extremely grateful to Barry for stepping in at a critical time for Network TEN.
“He was hired to stabilise and restructure Network TEN’s Sales department, and to find a successor. He achieved those objectives, and more.
“Barry is one of Australia’s most experienced media executives. He has been a key member of Network TEN’s executive team over the past 13 months and we wish him the very best for the future.”
TEN National Sales Manager, Kylie Rogers, returns from maternity leave in late July and will report to Ms Barrett.
Hamish McLennan added: “Louise and Kylie are highly experienced and effective executives, with great relationships across the marketing and media industries. They will make a powerful combination.”