EchoStar, parent of the Dish Network Satellite Television service, said the deal values Sling Media at approximately $380 million, payable in cash and EchoStar options.
The transaction is expected to close in the fourth quarter of 2007, EchoStar said.
The Slingbox connects cable and satellite TV set-top boxes to the Internet. As a result, cell phones and other Web-connected devices can show what's on a customer's living room TV.
Since its launch some two years ago, big media companies have eyed Sling warily as companies attempt to forge their own Internet strategies to reach viewers wherever they spend time.
"EchoStar's acquisition of Sling Media will allow us to offer innovative and convenient ways for our customers to enjoy their programming on more displays and locations, including TVs, computers and mobile phones, both inside and outside of the home," said Charlie Ergen, CEO and co-founder of EchoStar, in a statement.
Sling will become a wholly owned subsidiary of EchoStar, with no changes planned for Sling's senior management. The acquisition doesn't change any of the products and services currently scheduled to be released, said Sling spokesman Brian Jaquet.
Theannounced in January still has yet to be released, but the company says it is on track for release sometime before the end of this year. There have also been of the Slingbox waiting in the wings.
The large infusion of capital will be a boon for research and development at the Foster City, Calif.-based company.
"This is a large step forward for what we're trying to do with out products," said Jaquet. "We are going to continue to make great products with resources we didn't have before."
Sling Media says having Echostar as a parent company won't change the interoperability of its products with set-top boxes made by Echostar rivals. Sling announced a partnership with DirecTV last week in which it will co-operate the satellite provider's NFL Supercast service.
CNET News.com's Erica Ogg contributed to this report.