As previously reported, Kibu disclosed its plans to shut down at a staff meeting last Friday. At the time, Kibu also laid off most of its 65-person staff.
Although the Kibu Web site still was operating Friday, a skeleton staff was completing plans for the site to go dark, officials said.
Kibu offered content and chat rooms aimed at teenage girls.
The company was founded in 1999 and attracted a $22 million investment from Internet heavyweights including former Netscape co-founder Jim Clark, former Excite@Home chairman Tom Jermoluk, and venture capital firm Kleiner Perkins Caufield & Byers.
Other Web sites, such as Snowball.com, Alloy.com and Bolt.com, recently have emerged targeting the growing number of teens jumping online.
Internet research company Jupiter Media Metrix estimates that 47 percent of teens use the Internet.