Background: Astaxanthin is a lipid-soluble carotenoid with antioxidant and anti-inflammatory properties, but its effects on exercise performance and post-exercise recovery remain uncertain. This systematic review and meta-analysis aimed to evaluate the effects of astaxanthin supplementation on exercise performance and recovery-related biomarkers in healthy participants and athletes. Methods: This review followed PRISMA 2020 guidelines. PubMed, Web of Science, Embase, EBSCO, the Cochrane Library, and CNKI were searched from inception to January 2026. Randomized controlled trials comparing oral astaxanthin supplementation with placebo or control were included. Performance outcomes included VO₂max, time-trial or endurance-related performance, and maximal workload or power output. Recovery-related outcomes included creatine kinase, lactate dehydrogenase, malondialdehyde, interleukin-6, and related biomarkers. Standardized mean differences with 95% confidence intervals were pooled. Results: Twenty-four RCTs were included. Astaxanthin significantly reduced creatine kinase levels (SMD = −0.45, 95% CI: −0.83 to −0.07). Lactate dehydrogenase also favored astaxanthin (SMD = −0.93, 95% CI: −1.39 to −0.48), although heterogeneity was substantial. No significant effects were observed for malondialdehyde or interleukin-6. Astaxanthin did not significantly improve VO₂max, time-trial performance, or maximal workload/power output. Conclusions: Current evidence suggests that astaxanthin may be more beneficial for post-exercise recovery than for direct performance enhancement. The most consistent effect was observed for creatine kinase, whereas the LDH finding should be interpreted cautiously. Further well-powered trials with standardized dosing, duration, exercise protocols, and outcome assessments are needed.