The merger creates a potent combination of Web information directed toward families. It will carry the name Family.com and be included with Disney's newly launched site for children, DailyBlast.
The company will charge $4.95 a month or $39.95 annually for access. Many of Family Planet's popular features will remain, such as advice columns, features on games and activities, and electronic greeting cards.
Disney said it will take about six weeks to complete the combination. Financial terms were not disclosed.
The merger, which had been rumored for months, follows Disney's purchase of a "significant stake" in Starwave to create a real-time news Web site, ABCNews.com.
Disney hopes to transfer its success in family entertainment in theme parks, movies, and videos to the Web.
It is one of the handful of companies that is charging, however. Many analysts are dubious that users will be willing to pay for Web content, but Disney stands a good chance, its executives say.