High inputs of fertilizer nitrogen (N) in tea fields lead to declining soil pH and high emissions of N₂O. Amending the soil with biochar can potentially reduce N₂O emissions and alleviate soil acidification. To assess the multi-year effects of wheat straw-derived biochar on N₂O emissions and tea yield in tea fields, a three-year (2014–2016) field trial following the wheat straw-derived biochar addition was conducted in a tea plantation in southern China under three treatments, namely, conventional treatment (CON, application of conventional organic-chemical fertilizer without biochar), and treatments with conventional organic-chemical fertilizer + straw-derived biochar addition at 10 t ha⁻¹ (BC10) and 40 t ha⁻¹ (BC40) applied once at the beginning of the experiment. Compared to BC10 treatment, the annual total N₂O emissions of BC40 were increased by 32.0–46.2% in 2015 and 2016 (p ＜ 0.05) while no significant difference was found between BC10 and CON (p = 0.32–0.97), and N₂O emissions of BC10 showed a declined trend during the three years. An increase in tea yield of 24.2–26.0% (p ＜ 0.05) was also observed in BC10 treatment in 2015 and 2016 relative to CON. Differences between treatments in NH₄⁺-N were mostly significant (p ＜ 0.05) but not in NO₃^--N and DOC (p = 0.16–0.81). The BC40 treatment significantly raised soil pH relative to the CON (p < 0.05). Our collective data indicated that N₂O fluxes were positively correlated with the abundance of nirK-denitrification gene during the tea-growing season (p ＜0.05). Long-term impact of straw-derived biochar amendment on N₂O was inconsistent with previous short-term biochar studies in tea field soil. Our results indicated that wheat straw-derived biochar amendment at a low rate (BC10) into tea field soil is more feasible for reducing yield-scale N₂O emissions in the studied tea field system.