<p>Driven by their outstanding optoelectronic properties, two-dimensional (2D) materials have attracted significant attention in solar cells, LEDs, and other optoelectronic fields. Besides, the strain effect has served as a powerful approach to enhance the optoelectronic performance of 2D materials. This study employs first-principles calculations to investigate the tunable optoelectronic properties of monolayer <i>C</i>2/<i>m</i>-SnX (X = P, As) materials under uniaxial/biaxial strains ranging from -10% to 10%. The results demonstrate that under uniaxial/biaxial strains ranging from -10% to 10%, the structure of <i>C</i>2/<i>m</i>-SnX (X = P, As) maintains good stability. Their electronic and optical properties can uphold semiconductive characteristics unchanged across the entire strain conditions. Under different strains, their mechanical and optical properties are anisotropic. All of the outcomes above attest to their favorable flexibility. In addition, their mechanical, electronic, and optical properties display different and regular patterns of change under the modulation of various strains. In our opinion, this study not only validates the potential of <i>C</i>2/<i>m</i>-SnX as a strain-tunable flexible semiconductor but also furnishes a theoretical basis and directive for the future application in practice, where the application of strain can enable targeted regulation of its mechanical and optoelectronics properties, thus transforming and broadening its performance manifestations.</p>