The promotion announced Tuesday marks Rascoff's fourth different job with Seattle-based Zillow. He was previously the company's chief financial officer and vice president of marketing before being appointed COO two years ago.
Barton, 43, had been Zillow's CEO since its 2005 inception. He intends to remain involved in Zillow as executive chairman.
Rascoff, 34, co-founded the online travel service Hotwire.com, which was sold to IAC/InterActiveCorp in 2003 for $675 million. He moved over to Expedia.com, another Internet travel agency owned by IAC, before joining Zillow in 2005.
Zillow is best known for providing estimated property values of homes throughout the U.S. The privately held company says it's profitable, but hasn't disclosed any specifics.