Woozworld, maker of a user-generated virtual world for kids ages 9 to 14, has raised $6 million.

The company will use the money to expand Woozworld to mobile platforms and boost its marketing for the virtual world. It’s one more sign that game companies that get a foothold on the web are scrambling to establish themselves in the fast-growing mobile apps market as well.

Over the last 18 months, Woozworld users have registered more than 7 million virtual characters, known as avatars, and have built more than 14 million virtual spaces.

In Woozworld, tweens can build their own worlds to set up virtual businesses such as restaurants or games. The company says it gets more than 15 million monthly unique visitors from 180 countries and has 76 million monthly page views. Its user base has tripled over the last six months. Active users play for more than 70 minutes a day.

The money came from Telesystem and iNovia Capital as well as unnamed angel investors. Bernard Gerson, a former senior vice president of Disney, has joined the board. Gershon is currently president of GershonMedia, a digital media strategy practice. Eric Brassard, chief executive, said the company’s goal is to make Woozworld the No. 1 safe destination for tweens.