Given the challenges in uniformly enhancing the comprehensive performance of asphalt through single-fiber modification, this study multi-scale hybrid fibers was employed to develop hybrid fiber-modified asphalt. The objective was to exploit the synergistic crack-resistant mechanisms of diverse fiber materials across varying scales, thereby improving the strength and toughness of fiber-reinforced asphalt concrete. Specifically, basalt fiber (BF) and calcium sulfate whisker (CSW) were selected to fabricate hybrid fiber-modified asphalt mastics. Conventional physical and mechanical tests were conducted to systematically evaluate their reinforcement effects, with the optimal hybrid fiber dosage preliminarily identified through range analysis. Furthermore, optical microscopy was utilized to characterize the microstructural modification mechanisms and dispersion homogeneity within the hybrid fiber-modified asphalt mastics. Results demonstrated that the incorporation of CSW and BF significantly reduced the penetration and ductility of base asphalt while progressively increasing the softening point of modified mastics, indicating enhanced high-temperature stability. The optimal performance balance was achieved at 5% CSW, 1.0% BF (6 mm length). Microscopic analysis revealed distinct reinforcement mechanisms: CSW exhibited superior compatibility with asphalt, functioning as a particulate reinforcement phase, whereas BF demonstrated moderate compatibility, primarily contributing to crack-bridging and toughening effects within the mastic matrix.