Most paddy fields in China are potassium (K) insufficient, while soil inorganic amendments such as zeolite are good strategies to increase soil K content. There is limited information on the interactive effects of zeolite and K applications on rice (Oryza sativa L.) productivity, apparent K balance, and soil K balance. This two-year field study using a split-plot design with three replicates investigated the effects of zeolite and K applications on grain yield, soil available K dynamics, apparent K balance, and soil K balance in a paddy rice system. The main plots were three zeolite application rates (0, 5, and 10 t ha⁻¹; Z₀, Z₅, and Z₁₀). Within each main plot were subplots subjected to three K application rates (0, 30, and 60 kg ha⁻¹; K₀, K₃₀, and K₆₀). Zeolite was only applied in the first year while K was applied in both years. Results revealed that zeolite and K application, alone or in combination, significantly increased rice grain yield and economic benefit (based on resource inputs and grain value). In both years, the combination of 5 t ha⁻¹ zeolite with 30 kg ha⁻¹ K fertilizer (i.e., Z₅K₃₀) increased grain yield by up to 6.4% and economic benefit by up to 6.6%, relative to the most commonly used practice (i.e., Z₀K₆₀). With 5 and 10 t ha⁻¹ zeolite amended, the highest K application rate (K₆₀) did not further increase grain yield, but it decreased economic benefit, relative to the lower K application rate (K₃₀). Zeolite and K application, alone or in combination, significantly increased topsoil (0–30 cm) average available K content, post-harvest aboveground K uptake, and apparent K balance in the paddy rice system. Zeolite and K application alone significantly increased soil K balance. The results of this study demonstrated that zeolite amendments increased topsoil available K, enhanced rice K uptake, alleviated negative K balance, and improved productivity and agricultural profitability of paddy cultivation. The recommended treatment Z₅K₃₀ is suitable for rice cultivation due to its higher economic and environmental benefit as compared with the commonly used farmer practices.