Boost Mobile is a prepaid wireless service provider in the United States based in Irvine, California, a wholly owned division of Sprint Nextel operating within the Sprint Prepaid Group.

Boost Mobile provides wireless services using Sprint's CDMA, iDEN, and WiMAX networks.

Boost Mobile was originally launched in Australia and New Zealand in 2000. In Australia, wireless provider Optus also offers wireless service under the Boost Mobile brand.

Boost Mobile was founded in Australia and New Zealand in 2000 by Peter Adderton. Peter Adderton and Craig Cooper brought it to the United States in 2001, and entered into a joint venture with Nextel Communications to launch and market the brand - primarily to be marketed specifically to the urban community. A lure of Boost Mobile with the urban minority customer groups was that Boost's Walkie Talkie (Nextel's Direct Connect), for $1 a day ($30 per month), was the only way in the early 2000s (decade) to have something similar to unlimited voice minutes, and the advertisements effectively used "jive" or "slang" vocabulary. Boost Walkie Talkie only reached other Nextel/Boost IDEN subscribers, and as a form of push-to-talk (PTT), was half duplex. Unlimited voice plans on national carriers such as AT&T existed as early as 2001, but many people were unaware of this; AT&T eventually dropped their unlimited minutes calling plans. In 2003, Nextel purchased the American division of Boost Mobile. Until late 2004, Boost Mobile was only available in selected markets, primarily in California and Nevada. Prior to their purchase of Boost Mobile, Nextel primarily focused on the business market.