Sirius Satellite Radio is one of two satellite radio (SDARS) services operating in the United States and Canada, along with XM Satellite Radio. Headquartered in New York City, with smaller studios in Los Angeles and Memphis, Sirius was officially launched on July 1, 2002 and currently provides 69 streams (channels) of music and 65 streams of sports, news and entertainment to listeners. Music streams on Sirius carry a wide variety of genres, broadcasting 24 hours daily, commercial-free. A subset of Sirius music channels is included as part of the Dish Network satellite television service. Sirius channels are identified by Arbitron with the label "SR" (e.g. "SR120", "SR9", "SR17").

With most Sirius-enabled radios, the user can see the artist and song information on display while listening to the stream. The streams are broadcast from three satellites in a tundra orbit above North America.

Its business model is to provide pay-for-service radio, analogous to the business model for premium cable television, in which music channels are free of commercials. Talk channels such as Howard 100 and 101 do have regular commercials. Subscriptions are prepaid, with at least three months purchased at a time, and range in price from US$12.95 monthly (US$6.99 for each additional receiver) to US$499.99 for lifetime subscription. There is a US$15 activation fee for every radio activated. Sirius announced it had achieved its first positive cash flow quarter for the period ending December 2006.

Sirius was founded as Satellite CD Radio, Inc., which it was known by until the change to its current designation on November 18, 1999. The name is derived from Sirius, sometimes referred to as the Dog Star, the brightest star in the night-time sky, and was developed by the company's founder David Margolese, and its Marketing Chief Ira Bahr The dog in the Sirius logo is unofficially named "Mongo", a name garnered from the debut of Sirius Satellite Radio’s sponsorship on Casey Atwood’s and later Jimmy Spencer’s NASCAR entry, when the announcing cast voted on names. "Mongo" later became NASCAR driver Spencer’s nickname with the NASCAR Broadcasters (mainly Darrell Waltrip) in the following races.

On October 16, 2006 Sirius announced that it would be launching Sirius Internet Radio with 78 of its 135 channels being available worldwide on the internet to any of its subscribers with a valid user name and password.