<p>Climate change mitigation increasingly relies on enhancing terrestrial carbon sinks. Among these, phytolith-occluded carbon (PhytOC) offers a uniquely stable, long-term carbon storage mechanism. This study investigates the influence of temperature and precipitation on PhytOC accumulation in leaves of the sympodial bamboo <i>Bambusa emeiensis</i> over a 3-year period (2022–2024) in Wuhan, Central China. Leaf samples were collected every 10&#xa0;days, with phytoliths extracted via microwave digestion and analyzed by alkaline spectrophotometry. Results revealed a consistent seasonal pattern: PhytOC accumulation increased from winter to summer, peaking between July and August (up to 59&#xa0;g·kg⁻¹), and declined towards autumn. Strong positive correlations existed between temperature and PhytOC at both 10-day and monthly scales (<i>r</i> = 0.72–0.93, <i>p</i> &lt; 0.05), supported by statistically significant ANOVA tests. Precipitation, in contrast, exhibited a weaker and inconsistent relationship with PhytOC, acting primarily as a modulating rather than a primary factor. However, an extreme drought event in 2022 caused a 28.8% decline in PhytOC accumulation during peak summer months despite high temperatures. These findings demonstrate that temperature is the primary driver of PhytOC accumulation in <i>B. emeiensis</i>, with precipitation playing a secondary, scale-dependent role. The results highlight the significant climate-responsive carbon storage potential of sympodial bamboo forests and support the promotion of <i>B. emeiensis</i> in forest-based carbon management and nature-based climate solutions.</p>