This study investigates the impedance characteristics of ultrathin tattoo electrodes fabricated using a cost-effective, large-area deposition method. The electrodes are based on a Parylene C nanofilm, representing their core structure, with a blend of two PEDOT:PSS ink formulations serving as the active material in the recording area. Impedance measurements were conducted on five human participants under controlled conditions, covering the frequency range relevant for biopotential acquisition, from 20 to 1000 Hz. Moreover, to assess temporal stability, recordings were repeated three times over one hour for each subject. The resulting data were then modelled to characterize the electrical properties of the skin–electrode interface thus obtaining an equivalent circuit. Results demonstrate that tattoo electrodes exhibit impedance performance in the range of the standard electrodes, while offering added benefits such as enhanced conformability, stronger adhesion to the skin, and reduced irritation. These outcomes highlight the promise of Parylene C-based tattoo electrodes as a viable platform for next-generation low-cost and ultra-conformable electrodes and wearable bioelectronics devices.