A novel miniaturized millimeter-wave (mmWave) dual-polarized (DP) active phased array antenna is proposed for the fifth generation (5G) application in this letter. The slotted patch antenna element only occupies 4 × 4 mm 2 with a −10 dB | S 11 | bandwidth from 24.25 to 29.5 GHz. Four quasi-monopoles are added for wider bandwidth and beamwidth realization. Defective ground structure technology is adopted to remove the scanning blind spot. Using the DP eight-channel beamformer chips and multilayer printed circuit board technology, an active 8 × 8 phased array is designed, fabricated, and measured. Measured results show that the proposed antenna array can steer up to ±50° with a cross-polarization level lower than 22 dB. In summary, this phased array can be a good choice for 5G mmWave application considering the miniaturized, low-profile, wide bandwidth, and compact characterisitic.