A new micro-ocean-bottom electromagnetic (EM) receiver is presented for marine magnetotelluric (MT) and controlled-source EM (CSEM) data acquisition, avoiding the bulkiness, high cost, high power consumption, and narrow bandwidth of the existing ocean-bottom EM receivers. The efficient, compact, and easy-to-use data logger employs a single 17-in. spherical glass as a float and uses an acoustic telemetry modem unit to control the burn-wire release of the seafloor instrument via a smartphone. The receiver design involves two induction coils for the magnetometer and four 8-m-span electric-field sensors for MT and CSEM data acquisition. The new ocean-bottom EM receiver was tested in sea. Compared with other miniaturized seabed EM receivers, the proposed receiver achieves better comprehensive performance for MT and CSEM data acquisition and meets the requirements of deep-mantle-structure research and seabed resource exploration.