This study aims to evaluate the effect of gibberellin (GA₃) on the regulation of flowering and fruit development of red dragon fruit (Hylocereus polyrhizus) during the off-season period. The research was conducted in Banyuwangi, Indonesia, using a single-factor Randomized Block Design (RBD) consisting of five GA₃ concentrations: 0, 200, 400, 600, and 800 ppm. The observed parameters included the time to first flowering, number of flowers, number of fruits, fruit weight, fruit volume, peel thickness, sugar content (°Brix), and anthocyanin content. Analysis of variance showed that GA₃ application had a highly significant effect (p < 0.01) on flowering time, flower and fruit number, fruit weight, and fruit volume, but did not significantly influence peel thickness or sugar content. Concentrations of 400–600 ppm produced the most favorable physiological responses, accelerating flowering time, increasing flower and fruit numbers by up to twofold compared with the control, and significantly enhancing fruit weight and volume. A negative correlation between GA₃ concentration and flowering time (r = –0.81*) indicated accelerated generative transition, while a positive correlation between GA₃ and yield (r = 0.92*) confirmed improved reproductive efficiency. GA₃ stimulated floral meristem differentiation by enhancing the expression of FLOWERING LOCUS T (FT) and LEAFY, reducing DELLA protein activity, and strengthening photosynthate translocation to generative organs. These findings demonstrate that GA₃ application at 400–600 ppm can serve as an effective agronomic strategy to extend the production period, increase yield, and maintain fruit quality of red dragon fruit under tropical off-season conditions.