Internet Brands is being sold by sponsors Hellman & Friedman and JMI Equity Fund, which invested in 2010. The deal is valued at $1.1 billion, according to a New York Times report.
One source familiar with the transaction said that KKR will not break the brands up, and will "focus on growing its software solutions offerings."
KKR did not respond to a request seeking comment. A source familiar with the transaction said there are no changes anticipated with Internet Brands' management and its headquarters will remain based in California.
Sites operated by El Segundo, California-based Internet Brands include DoItYourself.com, Wikitravel, CarsDirect, CorvetteForum and Apartment Ratings, among others.
The company focuses on legal, home/travel, autodata solutions and health brands.
"Internet Brands is at an exciting inflection point of growth as the company transitions from a portfolio of web assets to a vertically integrated provider of media and client software solutions," said Herald Chen, co-head of KKR's technology investment group.