March will report to Fru Hazlitt, managing director for ITV commercial and online. He is currently head of digital media, news sport and weather at ITV and had previously held the role of head of digital at Sky News.
The departure of Pembrooke is part of a wider restructure of the digital and on-demand departments at ITV, with up to 40 non-commercial staff in the 100-strong departments understood to have been warned by ITV this morning (5 July) that their roles could be placed under consultation over the coming days.
March will be responsible for "the strategy and delivery of all of ITV's online activity and products", as the commercial broadcaster focuses on "broadcast content, sponsored interactive programme experiences, building online communities using social media, and the continued distribution of the ITV Player across multiple platforms," according to ITV.
Hazlitt said: "Julian has done a fantastic job delivering our hugely successful relaunched news and sport sites and I'm delighted that he'll be taking on this wider remit across our digital portfolio as we deliver the next phase of our online transformation."
March said: "It's an exciting time for ITV Online. Our new integrated Pay player is in final consumer testing, ITV Player is available on more platforms than ever before, and some huge communities are following and interacting with our programme brands in the digital space.
Pembrooke said: "I've enjoyed my time at ITV and I'm proud of the team's achievements with ITV Player, second-screen apps, and the relaunch of ITV News. With ITV Player launching on YouView, and our new Pay player moving into final consumer testing, this feels like an appropriate time to be moving on."
Pembroke is understood to be leaving of his own volition, but is departing without a job to go to.
He moved to ITV in August 2010 after more than three years at Global Radio, where he was group director of online and interactive.
Follow Mark Banham on Twitter @Banham72