Comcast owns NBCUniversal and is the nation's largest residential Internet provider, with almost 20 million broadband subscribers.
Ezra Cooperstein, Fullscreen's chief operating officer, said the company could be the "network model of tomorrow" and targets its entertainment toward younger viewers.
Fullscreen's network of affiliated channels generates 2.5 billion YouTube views a month and reaches about 150 million subscribers who follow its channels, the company says.
Fullscreen helps performers manage their YouTube presence and find advertisers. Fullscreen takes a small cut of the advertising for revenue.
The 160-employee Fullscreen is profitable, Cooperstein said. The Comcast-related venture investment will be used to create original programming for Fullscreen and help it expand globally. Competitors include Maker Studios Inc. and Machinima.
One Fullscreen-affiliated channel features the violinist Lindsey Stirling, whose "Crystallize" video has been viewed more than 62 million times. Stirling recently signed with Lady Gaga's talent manager, Troy Carter, who was raised in Philadelphia.
Comcast invested in Fullscreen through its corporate venture-capital fund, which has offices in Silicon Valley, Philadelphia, and New York.
"As the video ecosystem evolves rapidly, Fullscreen is fusing technology and services to simplify operations and maximize opportunity for brand marketers and creators," Sam Landman, principal at Comcast Ventures, said in a statement.
In addition to emerging YouTube entertainers, Fullscreen helps traditional networks on YouTube. NBC was the first entertainment network to use Fullscreen to manage its presence on YouTube, Landman said.
"There has been explosive growth in online video, particularly on YouTube, and a growing demand from our clients to reach consumers on its platform as it revolutionizes youth media consumption," said Mark Read, the chief executive officer of WPP Digital.
Contact Bob Fernandez at 215-854-5897 or firstname.lastname@example.org or follow on Twitter @bobfernandez1.