A multifunctional narrow-linewidth laser and photonic microwave generation using a monolithic integrated amplified feedback laser under delayed optical feedback is demonstrated. The device can work in signal-mode and dual-mode states by varying the injection currents of laser sections. Photonic microwave is generated by mode-beating of the two laser modes. Through a dual-loop all-optical feedback, the linewidths of both the signal-mode optical signal and photonic microwave signal are reduced by more than three orders of magnitude. Single mode operation with 2.6 kHz linewidth and photonic microwave generation at 37.97 GHz with 1.6 kHz linewidth are experimentally realized.