This paper proposes to apply LLC resonant inverters with constant-current control for an ozone-driven system. This study is motivated because the ozone-driven system often needs to connect an extra transformer to boost the voltage, resulting in a larger size of the system. Therefore, based on the design of transformer turn ratio and transformer leakage inductance and resonant capacitor, the study suggests a LLC circuit used in the ozone-driven system such that the transformer cost can be largely saved while reaching the expected voltage level more flexibly. Furthermore, through the voltage detection of resonant capacitors along with the microcontroller unit, a constant-current output can be well maintained. This proposed circuit has been realized with hardware implementation. Experimental results support the practical values of this proposed circuit for industry applications.