Amorphous Sm–Co films with uniaxial in-plane anisotropy have great potential for application in informationstorage media and spintronic materials. The most effective method to produce uniaxial in-plane anisotropy is to apply an in-plane magnetic field during deposition. However, this method inevitably requires more complex equipment. Here, we report a new way to produce uniaxial in-plane anisotropy by growing amorphous Sm–Co films onto (011)-cut single-crystal substrates in the absence of an external magnetic field. The tunable anisotropy constant, k_A, is demonstrated with variation in the lattice parameter of the substrates. A k_A value as high as about 3.3 × 10⁴ J·m⁻³ was obtained in the amorphous Sm–Co film grown on a LaAlO₃(011) substrate. Detailed analysis indicated that the preferential seeding and growth of ferromagnetic (FM) domains caused by the anisotropic strain of the substrates, along with the formed Sm–Co, Co–Co directional pair ordering, exert a substantial effect. This work provides a new way to obtain in-plane anisotropy in amorphous Sm–Co films.