Two and a half years after James Zarley took the helm of ValueClick, the digital marketing company said he’s being replaced by new president and CEO John Giuliani.

Giuliani, who’s been the Westlake Village-based firm’s chief operating officer since April, will step into his new role immediately. He succeeds Zarley, who has been the marketing firm’s CEO since April 2010 and from 1999 to 2007. Zarley will stay on with ValueClick as the executive chairman of its board of directors, according to a Dec. 5 news release.

Giuliani was CEO of Dotomi at the time it was acquired by ValueClick in August 2011, and he was president of that division until he became the company’s COO.

“This is the perfect time to expand John’s role, considering the company’s momentum under his leadership. His early success in bringing our assets together has shown he has the expertise and experience to lead ValueClick through its next phase of growth,” Zarley said in a news release. “It gives me great pleasure to welcome John as our new CEO. I am excited about our current growth and outlook for the future, and I look forward to assisting him and the team in expanding ValueClick’s leading position in the digital marketing industry.”

ValueClick is one of the largest digital marketing companies in the world. In addition to Dotomi, the firm’s brands include Commission Junction, ValueClick Media, Greystripe, Mediaplex, Smarter.com, CouponMountain.com, Investopedia.com and PriceRunner.