This letter presents an optical current sensor (OCS) for high-voltage dc networks. The proposed OCS combines electrical signal conditioning circuit and a low-voltage transducer (LVT) based on piezoelectric and photonic technologies. The characterization of the OCS individual components was performed in laboratory conditions, and the sensor operation was evaluated based on the current measurement range set by the IEC 61869-14 standard. The experimental results demonstrated that the device can be used under the input current range conditions specified in IEC 61869-14 and has the potential to provide current measuring functionality in challenging locations that impose limitation on conventional sensors.