In this Letter, we present a highly efficient 1.55-µm buried heterostructure distributed feedback (BH-DFB) laser diode. The optimized epitaxial structure resulted in a threshold current of 12 mA and a differential slope efficiency of 0.433 W/A. The laser exhibited stable single longitudinal mode characteristics in both high current injection and broad temperature range testing. Additionally, the ns-level pulsed operation characteristics of the BH-DFB laser were verified, achieving a pulse peak power of 6.27 W with a pulse optical width of 20.4 ns. The watt-level pulse optical power was achieved with a single active region. With its eye-safe wavelength, high operating efficiency, stable single-mode spectral characteristics, and high pulse optical power, the 1.55-µm BH-DFB laser is a promising light source for LiDAR systems.