The event was first announced by WEC President Reed Harris on the Dave and Mahoney Show. Jamie Varner was expected to face Kamal Shalorus at this event, but that bout was called off due to an injury sustained by Shalorus. The match was later rescheduled for WEC 49 on June 20, where both men fought to a split draw. A bout between Alex Karalexis and Zach Micklewright was due to take place at this event, but Micklewright suffered a broken ankle and was later replaced by Anthony Pettis. Antonio Banuelos was scheduled to face Damacio Page at the event, but Page was forced off the card with an injury. Banuelos ending up facing Scott Jorgensen, in a rematch of their bout from WEC 41 which Banuelos won via split decision. Cub Swanson was scheduled to face WEC newcomer Chan Sung Jung at this event, but Swanson was forced from the card with an injury. He was replaced by Leonard Garcia. Mackens Semerzier was scheduled to face Anthony Morrison at this event, but Semerzier was forced from the card with an injury and was replaced by Chad Mendes. Veteran UFC commentators Mike Goldberg and Joe Rogan handled broadcast duties for the event. Bruce Buffer handled the fighter introductions. Two of the night's preliminary fights aired on Spike TV, marking the only time that Spike would air live WEC fights before their dissolution. The advertising & live broadcasts for WEC 48 omitted virtually all references to the WEC brand, with the only exceptions being early versions of the poster, one mention during the broadcast by Joe Rogan, and the WEC logo on the championship belts themselves. During the broadcasts, the announcers referred only to "the organization" while the WEC logo was removed from the cage and the fighters' gloves.
The following is the reported payout to the fighters as reported to the California State Athletic Commission. It does not include sponsor money or "locker room" bonuses often given by the WEC and also do not include the WEC's traditional "fight night" bonuses.
José Aldo: $40,000 def. Urijah Faber: $28,000
Benson Henderson: $26,000 def. Donald Cerrone: $14,000
Manvel Gamburyan: $36,000 def. Mike Brown: $21,000
Shane Roller: $28,000 def. Anthony Njokuani: $7,000
Scott Jorgensen: $21,000 def. Antonio Banuelos: $7,000
Leonard Garcia: $28,000 def. Chan Sung Jung: $5,000
Anthony Pettis: $8,000 def. Alex Karalexis: $10,000