The majority of existing effective stress-based constitutive models approach thermal effects through the temperature dependency of surface tension and its effects on the soil-water retention curve (SWRC) and effective stress. Experimental tests and theoretical studies, however, suggest that the temperature effect on surface tension alone is not sufficient to properly explain thermal-induced changes in the effective stress and SWRC. This study focuses on the temperature-dependent elastoplastic behavior of low plasticity unsaturated soils by developing a set of constitutive-level relations that incorporate temperature-dependent SWRC and effective stress models. These models account for the effect of temperature on the enthalpy, contact angle, and surface tension. The application of the presented constitutive relations was demonstrated and validated for low plasticity soils, specifically incorporating temperature effects into the hardening modulus, specific volume change, yield stress of the modified Cam-Clay model, and stress-strain relationships. The proposed relationships are incorporated in any effective stress-based constitutive model for modeling temperature dependency of elastoplastic response in low plasticity unsaturated soils. Employing these relationships can enhance the numerical simulation of low plasticity unsaturated soils under thermo-mechanical or other coupled processes involving temperature-dependent conditions.