Grape is a globally significant fruit-bearing crop, and the grape flower bud differentiation essential to fruit production is closely related to light quality. To investigate the regulatory mechanism of grape flower bud differentiation under red‒blue light, the transcriptome and hormone content were determined at four stages of flower bud differentiation. The levels of indole-3-acetic acid (IAA) and abscisic acid (ABA) in grape flower buds at all stages of differentiation under red‒blue light were higher than those in the control. However, the levels of cytokinins (CKs) and gibberellic acid (giberellins, GAs) fluctuated continuously over the course of flower bud differentiation. Moreover, many differentially expressed genes were involved in auxin, CK, GA, and the ABA signal transduction pathways. There were significant differences in theAUX/IAA,SAUR,A-RR, andABFgene expression levels between the red‒blue light treatment and the control buds, especially in regard to theABFgenes, the expression levels of which were completely different between the two groups. The expression ofGBF4andAI5L2in the control was always low, while the expression under red‒blue light increased.AI5L7andAI5L5expression levels showed an upwards trend in the control plant buds and gradually decreased in red‒blue light treatment plant buds. Through weighted gene coexpression network analysis, we determined that the transcription factorsWRK48(WRKY family),EF110(ERF family),ABR1,CAMTA3(CAMTA family), andHSFA3(HSF family) may be involved in the regulation of theGBF4gene. This study lays a foundation for further analysis of grape flower bud differentiation regulation under red‒blue light.