White broke the news during a Q&A session with members of the military at Fort Hood prior to Friday's weigh-in event.
Pettis had been tentatively scheduled to face the winner of the Frankie Edgar-Gray Maynard lightweight title fight. But when that fight, at UFC 125 earlier this month, ended in a rare championship bout draw, White ordered an immediate rematch – putting Pettis in limbo.
Rather than waiting, Pettis, a Duke Roufus protege, will test himself against Guida, a member of Greg Jackson's camp.
The Pettis-Guida fight was rumored last week, and White suggested on a media call then that the bout was under consideration. But on Friday, with UFC matchmaker Joe Silva nearby, he said the fight will take place – though he did not indicate to the military fans in attendance when the fight might take place. MMA Junkie reported Friday, however, that the fight will serve as the main event for the Season 13 finale of "The Ultimate Fighter." Edgar and Maynard will rematch at UFC 130, which takes place at the MGM Grand Garden Arena on May 28.
Guida has won three straight fights, all by submission. At UFC 125, he submitted Pride legend Takanori Gomi in the second round. And Pettis is coming off a win in the WEC's swan song, WEC 53, in which he dethroned Ben Henderson – delivering an already-famous kick off the cage in the process. That gave Pettis four straight wins. His only career loss was a split decision setback to Bart Palaszewski at WEC 45.