Array antenna integrated with RF chip using InFO-WLP technology is proposed for millimeter wave system applications. Aperture-coupled patch antenna is designed on the fan-out molding compound (MC). The performance of single-element antenna is evaluated first and proved to have 5 dBi of gain. Meanwhile, the interconnect from chip to antenna feeding line is demonstrated to only have 0.7 dB loss, which can save 19 % PA output power compared with that of flip-chip package. Finally, the system performance of 4 × 4 antenna array integrated with RF chip on the InFO structure shows 14.7 dBi of array gain in a small form factor of 10 × 10 × 0.5 mm3.