A multiple-capillary Ar plasma jet was successfully generated by an advanced dielectric barrier discharge reactor. The reactor consisted of four quartz capillaries arranged separately and covered by two ring-shaped electrodes, which were isolated by a liquid dielectric. The advantages of the reactor included less Ar consumption (ranging from 1 to 3 L/min to obtain a total cross-sectional area of four individual plasma flow components of 3.14 mm2 at the capillary orifices) and low gas temperatures (not exceeding 40 °C). The obtained temperature is suitable for implementing various biomedical applications such as wound healing, dental treatment, and cancer therapy. Furthermore, the plasma jet spread when it interreacted with dielectric materials or skin, resulting in an enlarged effective plasma treatment area of approximately 8 mm2. Analysis of optical emission spectra of the plasma jet indicated the existence of several reactive species, suggesting that the plasma device holds potential for biomedical applications and material surface treatments.