Osteoarthritis (OA) is a degenerative joint disease characterized by the progressive loss of articular cartilage and chronic pain. Although cyclooxygenase-2 (COX-2) inhibitors such as celecoxib are recommended to patients at high risk of gastrointestinal (GI) adverse events, COX-2 inhibitors do not completely prevent GI adverse events. Rebamipide, a gastroprotective agent, has anti-inflammatory properties and acts as an oxygen radical scavenger. The aim of this study was to investigate the in vivo effects of coadministration of rebamipide and celecoxib in an OA rat model. OA was induced by intra-articular injection of monosodium iodoacetate. Oral administration of rebamipide was initiated on the day of OA induction. In this study, rebamipide showed antinociceptive properties and attenuated cartilage degeneration. Rebamipide reduced the expression of matrix metalloproteinase 13, interleukin-1β, inducible nitric oxide synthase, and nitrotyrosine in OA cartilage. OA rats treated with celecoxib in combination with rebamipide demonstrated a higher pain threshold than those treated with monotherapy. Histological examination also showed that the joints from OA animals treated with combination therapy demonstrated less cartilage damage than those of animals treated with monotherapy. We showed that the potential benefit of combination therapy with celecoxib and rebamipide on pain and cartilage degeneration in OA.