The laser powder bed fusion (LPBF) technique offers great flexibility in modifying alloy composition, leading to unlimited opportunities in the development of novel materials with remarkable properties. Such an advantage is expected to provide the solution to the challenge in conventional manufacturing techniques for increasing the boron composition of Inconel 718 above 60 ppm due to the formation of serious cracks. In this study, boron-enhanced Inconel 718 was manufactured using the LPBF technique with pre-mixed powder (Inconel 718 and boron). Optimized processing parameters successfully enabled the boron content to increase up to 5,000 ppm without defects (e.g., cracks, pores), which far exceeds the maximum limit (60 ppm) of conventional manufacturing methods. Combined with tailored post-heat treatment conditions, exceptional mechanical properties were achieved, while the formation of the detrimental phases (i.e., Laves phase, δ phase) was suppressed. At room temperature, tensile strength and microhardness were improved up to 38% and 37%, respectively, with increased boron contents compared to that of ordinary Inconel 718. At high temperature (650°C), boron-enhanced Inconel 718 showed outstanding tensile strength, which would allow it to withstand higher thermal stress. Boron-enhanced Inconel 718 showed great thermal cycling stability (between 650°C and 25°C) when the boron content was increased up to 1,000 ppm. The excellent mechanical properties and thermally stable microstructure position boron-enhanced Inconel 718 as a promising candidate for high-temperature applications (e.g., concentrating solar-thermal power, aeroengine, steam power plant).