The deal, expected to be completed within 45 days, is worth $204.8 million, New York-based Ziff-Davis said in a statement.
Ziff-Davis, which publishes several technology and media trade magazines, said ZDTV will continue to maintain certain business agreements that cover a joint news organization, such as co-development of promotions and audience programs, with ZDNet, its online publication, and ZD Publishing, once the deal is completed.
Today's investment made by Bellevue, Wash.-based Vulcan Ventures follows the company's earlier investment of 33 percent nine months ago in ZDTV, a 24-hour cable TV channel and integrated Web site focused on technology news.
Ziff-Davis said its ZDTV unit is distributed in more than 14 million U.S. homes and aims to reach approximately 16 million U.S. homes by year's end. ZDTV is offered through more than 400 cable systems as well as through satellite companies DirecTV and Echo Star.
Vulcan Ventures is an investor in CNET, publisher of News.com.