This paper proposes a new electromagnetic field (EMF) exposure system adopting a cavity bandpass filter and a mode-matching component for in vitro experiments at the 2.45 GHz ISM band. To the best of the authors’ knowledge, this is the first attempt to apply the cavity filter to the EMF exposure apparatus, offering a wide impedance bandwidth and metallic shielding. The introduced EMF exposure setup consists of two resonators operating in the TM01 mode, six 60° sectional resonators operating in the TM31 mode, and the holders for 35 mm Petri dishes. Each 60° sectional resonator and holder top act as a heating chamber and a mode-matching component, respectively. Petri dishes are placed on the holder tops at the mid-height of the heating chamber. Upon insertion of Dulbecco’s Modified Eagle Medium (DMEM) solutions, the HEM12δ mode is formed within each solution. From the perspective of field direction, the mode-matching element makes the field at the bottom of the Petri dish similar to that within the DMEM solution. This configuration effectively supports the formation of the HEM12δ mode in the solution, thereby enhancing the specific absorption rate (SAR) and efficiency (SAR per input power). The 1g-SAR for the DMEM solution with 2 mL per dish was demonstrated as 78.98 W/kg based on a 1 W RF input. The measured return loss was greater than 10 dB with the frequency ranges of 2.4 to 2.53 GHz, with a maximum return loss of 23.9 dB at 2.445 GHz. The proposed EMF exposure device provided a high level of efficiency considering SAR, RF input power, and cell culture conductivity compared with other structures. Furthermore, the radial EMF device helps ensure consistent SAR distribution across the six samples.