Due to the advantages of rich dynamics, small size and easy integration, semiconductor laser-based signal generation technology has become a potential candidate for high-performance microwave photonic signal generation. Under proper optical injection, semiconductor lasers can operate at the period-one (P1) oscillation state and break through the limitation of the intrinsic relaxation oscillation frequency to realize the generation of the widely tunable microwave signal. In addition, assisted by dynamical control of injection parameters, wideband reconfigurable microwave frequency-modulated (LFM) signals can be generated, which has important applications in radar systems. In this paper, the research progresses of the wideband radar signal generation and application based on an optically injected semiconductor laser were reviewed. Firstly, microwave LFM waveforms with large time-bandwidth products were successfully generated by exploring the controlled P1 dynamics of an optically injected semiconductor laser. The main operating parameters are adjustable, including the central frequency, bandwidth, frequency band, and temporal period. Secondly, a delay-matched optoelectronic feedback structure was introduced to greatly improve the spectral purity and phase coherence of the generated wideband radar waveform. Finally, by applying the generated wideband waveforms, a microwave photonic radar system was experimentally demonstrated, and its high-resolution target detection and imaging ability were verified.