Strain-tunable magnetic anisotropy and magneto-optical effects in a room-temperature <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Cr</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Te</mml:mi><mml:mn>3</

Two-dimensional intrinsic magnets with multiple magnetic atomic layers often allow the magnetic phase and the magnetic anisotropy transitions, providing a versatile platform for exploring monolayer spin valve and magneto-optical effects. Based on the first-principles calculations and Monte Carlo simulations, both spin valve and magneto-optical effects emerge from the strained ${\mathrm{Cr}}_{2}{\mathrm{Te}}_{3}$ monolayer. The ${\mathrm{Cr}}_{2}{\mathrm{Te}}_{3}$ monolayer is a ferromagnetic metal with an in-plane easy magnetization axis and a Curie temperature of 495 K. Under the tensile strain up to 4.2%, it transitions to an antiferromagnetic semiconductor. The direction of the easy magnetization axis changes to an out-of-plane direction during strains from 1% to 4%, and also induces a variance of the Kerr rotation angle through the magneto-optical Kerr effect. We provide a potential candidate material for the design of a future room-temperature monolayer spin valve and optospintronic devices.