Selenium (Se) biofortification in tea plants (Camellia sinensis) not only plays important roles in addressing global Se deficiency, but also has great potential to enhance the nutritional value of tea. This first meta-analysis synthesized data from 38 studies (comprising 797 paired observations) conducted in China, to evaluate the impact of Se fertilization strategies, cultivar selection, and harvest timing on Se accumulation and key quality components in tea leaves. Results indicated that Se fertilization significantly increased Se concentration in tea leaves by 484.1 % and improved tea quality by increasing amino acids (+7.1 %), soluble sugars (+18.2 %), total catechins (+16.1 %) and water extract (+1.6 %), while reducing the phenol-to-amino acid (TP/AA) ratio (−10.2 %). Selenate application had superior efficacy for Se accumulation compared to organic Se, followed by selenite and selenium nanoparticles (SeNPs). Selenite and SeNPs applications significantly increased amino acids and soluble sugar content, but selenite enhanced the caffeine content, whereas organic Se reduced it. Foliar fertilization was more effective than soil fertilization for Se accumulation, but soil fertilization significantly increased amino acids content while reducing caffeine levels. Tea cultivar was the most critical factor influencing Se accumulation in tea leaves, with ‘Lvgui 1’ showing the highest capacity. Mature tea plants (≥ 4 years old) showed higher tea quality, including lower TP/AA ratios and caffeine content, compared to younger plants (1–3 years old). Autumn-harvested tea exhibited the highest Se accumulation, followed by spring and summer. These findings highlight the importance of optimizing Se fertilization strategies, selecting high-accumulating cultivars, and timing harvests to maximize both Se content and tea quality. This study provides actionable insights for producing Se-enriched tea with enhanced nutritional and sensory properties.