Salicylic acid (SA) is a key signaling molecule involved in plant defense responses; however, its role in peanut defense against the cowpea aphid (Aphis craccivora Koch) remains poorly understood. This study investigated changes in endogenous SA content and the activities of two SA biosynthetic enzymes, phenylalanine ammonia-lyase (PAL) and benzoic acid 2-hydroxylase (BA2H), in the peanut cultivar CNC1 following infestation with 10, 20, or 30 wingless adult aphids per plant. Leaf samples were collected at 0, 24, 48, 72, and 96 h post-infestation (hpi). Aphid infestation induced SA accumulation, with the highest SA level recorded at 24 hpi in plants infested with 30 aphids. PAL activity was rapidly induced during the early stages of infestation, reaching a peak at 24 hpi, whereas BA2H activity exhibited a temporal pattern closely associated with SA accumulation. These results indicate that aphid feeding activates SA-mediated defense signaling in the peanut cultivar CNC1, probably through the coordinated induction of PAL- and BA2H-associated pathways. The findings provide physiological evidence supporting the involvement of SA signaling in peanut responses to A. craccivora infestation.