Laser diodes have recently gained attention as compact and affordable excitation sources for photoacoustic imaging, offering a balance between the high optical power of traditional lasers and the portability of LEDs. With pulse widths in the tens of nanoseconds and repetition rates up to several kilohertz, Laser diodes enable real-time, deep-tissue photoacoustic imaging with relatively simple and efficient driver electronics. In this chapter, we discuss key technical aspects of pulsed Laser diodes including emission wavelengths, pulse energy, and driver design, along with their integration in combined ultrasound–photoacoustic systems. Furthermore, we summarize preclinical and clinical pilot studies that have demonstrated the feasibility of laser diode-based photoacoustic imaging for various biomedical applications such as vascular, musculoskeletal, and dermatological imaging.