This paper focuses on the use of an electro-optic (EO) probe for the spatially and temporally resolved characterization of the electric field (E-field) associated with guided ionization waves-or guided streamers-propagating at atmospheric pressure. An AC high-voltage power supply (6 kV at 18 kHz) is used to generate guided ionization waves in helium with a cold atmospheric pressure plasma jet device (APPJ). The capabilities of this electro-optic technique are investigated with and without the discharge. This innovative technology will use to carry out the optical polarimetric analysis of the APPJ with simultaneous real-time measurement of longitudinal and radial components of the electric field vector. Last but not least, an application-based case study of the ionization waves propagating and interacting with the EO probebeing a solid dielectric target-is also reported. The results will bring realistic information on the potential perturbation induced by the EO probe itself on the E-field characterization at the macroscopic scale.