Introduction: The acute and isolated ingestion of sodium bicarbonate (NaHCO₃) and caffeine (CAF) improves performance and delays fatigue in high-intensity tasks. However, it remains to be elucidated if the coingestion of both dietary supplements stimulates a summative ergogenic effect. This study aimed to examine the effect of the acute coingestion of NaHCO₃ and CAF on repeated-sprint performance. Methods: Twenty-five trained participants (age: 23.3 [4.0] y; sex [female/male]: 12/13; body mass: 69.6 [12.5] kg) participated in a randomized, double-blind, placebo (PLA) -controlled, crossover study. Participants were assigned to 4 conditions: (1) NaHCO₃ + CAF, (2) NaHCO₃, (3) CAF, or (4) PLA. Thus, they ingested 0.3 g/kg of NaHCO₃, 3 mg/kg of CAF, or PLA. Then, participants performed 4 Wingate tests (Wt), consisting of a 30-second all-out sprint against an individualized resisted load, interspersed by a 1.5-minute rest period between sprints. Results: Peak (W_peak) and mean (W_mean) power output revealed a supplement and sprint interaction effect (P = .009 and P = .049, respectively). Compared with PLA, NaHCO₃ + CAF and NaHCO₃ increased W_peak performance in Wt 3 (3%, P = .021) and Wt 4 (4.5%, P = .047), while NaHCO₃ supplementation increased mean power performance in Wt 3 (4.2%, P = .001). In Wt 1, CAF increased W_peak (3.2%, P = .054) and reduced time to W_peak (−8.5%; P = .008). Plasma lactate showed a supplement plus sprint interaction (P < .001) when NaHCO₃ was compared with CAF (13%, P = .031) and PLA (23%, P = .021). Conclusion: To summarize, although the isolated ingestion of CAF and NaHCO₃ improved repeated-sprint performance, the coingestion of both supplements did not stimulate a synergic ergogenic effect.