The purpose of this study was to examine the effects of silane coupling agent modifications on the mechanical performance of the basalt fiber (BF)-reinforced acrylonitrile-butadiene-styrene (ABS) composites. Three different silane coupling agents were used. The mechanical properties of the composites were determined by the tensile, flexural, impact tests, and dynamic mechanical analysis (DMA). According to the test results, the tensile strength increased with the use of (3-aminopropyl) triethoxysilane (AP) and 3-(trimethoxysilyl) propylmethacrylate (MA), while the use of (3-glycidyloxypropyl) trimethoxysilane (GP) reduced the tensile strength. All the silane modifications improved the flexural strength and modulus and the highest improvement was achieved with the use of AP. No remarkable difference was observed in impact properties with the use of silane coupling agents. The addition of BF significantly improved the elastic modulus of the ABS regardless of the modification type, while the further improvements were achieved through the use of AP and MA. In brief, AP showed the highest performance among the studied silane coupling agents due to the covalent bond formation between the amino group of AP and the nitrile group of styrene-acrylonitrile (SAN) matrix.