This paper presents a broadband continuous class-B/J power amplifier (PA) based on a novel output matching network (OMN). In order to realize a compact and broadband OMN design, a multiband harmonic control network (MHCN) with a simple structure consisting of a combination of open-circuited stubs and a microstrip radial stub (MRS) is designed, which is capable of tuning the second harmonic impedance at the upper and lower sideband frequencies and at the center frequency well and consumes low power. Also, a fundamental matching network (FMN) is designed by means of the simplified real frequency technique (SRFT) algorithm of the computer-aided program, which improves the efficiency of the circuit design. Both of them satisfy the requirements of a wideband PA and enhance the frequency-selective performance of the OMN. For validation purposes, practical measurements of the designed and fabricated continuous class-B/J PA with size of 61 × 51 mm² have been carried out. The results show that at an operating frequency of 2.4–4.4 GHz, the 53%–73% drain efficiency (DE) at the output power of 38.4–42.4 dBm, and the maximum gain is 13.3 dB.