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As one of the most abundant elements in the Earth’s crust, semiconductor silicon has become the core material for microelectronics and optoelectronics. The silicon-based infrared (IR) photodetector can overcome the shortcomings of traditional IR materials in terms of manufacturing cost, environmental friendliness, and compatibility with the complementary metal-oxide–semiconductor (CMOS) technology. However, the band structure of silicon limits its application in IR photodetection, which is of great significance for silicon-based optoelectronic integrations. Ultrafast pulsed laser hyperdoping can extend the absorption to IR wavelengths below the bandgap of silicon. In this article, using femtosecond laser irradiation process, we fabricated inert argon-hyperdoped black silicon, whose absorption wavelength has been extended to 2500 nm. The combination of hyperdoping, laser ablation, and geometric microstructures enhances sub-bandgap absorption of argon-hyperdoped black silicon even though after thermal annealing. The argon-hyperdoped silicon photodiodes are fabricated based on metal-black silicon (n+)-silicon (n) double junctions, and the photodetector shows favorable photoresponse to 1310-nm IR light under both forward and reverse biases. The inert argon-hyperdoped black silicon, with lower ionized impurity scattering, shows a potential application in IR photodetection.