Seastrunk ran for 185 yards with a touchdown, while Martin added 113 yards and three TDs as Baylor (5-5, 2-5 Big 12) picked off Heisman Trophy candidate Collin Klein three times in the upset.
Nick Florence connected on 20-of-32 passes for 238 yards with two scores and a pair of interceptions for the Bears.
Klein finished 27-of-50 for 286 passing yards with two touchdowns for the Wildcats (10-1, 7-1), who will lose their No. 1 standing in the Bowl Championship Series rankings with the surprising setback.
Coupled with No. 3 Notre Dame's win over Wake Forest and No. 2 Oregon's overtime loss to Stanford, the Wildcats' one-sided setback all but knocks them out of contention for a national championship.
Alabama, ranked fourth in the BCS, trampled Western Carolina 49-0 Saturday.