To analyze the unstrained cable configuration of an asymmetric single-pylon single-span ground-anchored suspension bridge under temperature effects, an analytical method based on catenary theory is proposed. By integrating mechanical equilibrium conditions, geometric compatibility conditions, and the principle of unstrained cable length invariance, a system of control equations with an equal number of basic unknown parameters is established. This system of equations fully accounts for the coupled effects of pylon-top displacement and compound saddle rolling displacement on the unstrained cable configuration under thermal variations, with solutions obtained via the quasi-Newton method. The proposed method is validated through the engineering case of the Luzhijiang Bridge, followed by a parametric analysis of unstrained cable configurations under varying temperatures. Results demonstrate that the method efficiently calculates configurations under uniform temperature fields while quantifying impacts on cable elevation, longitudinal position, pylon-top displacement, and saddle rolling displacement. Specifically, cable elevation decreases with rising temperature whereas pylon-top displacement and saddle rolling displacement exhibit linear relationships with temperature; moreover, the thermal expansion-contraction effect of the main cable synergized with adaptive displacement of the pylon-saddle system significantly amplifies temperature responses in asymmetric suspension bridges. Field measurements under typical temperature conditions at Luzhijiang Bridge confirm that deviations between theoretical predictions and actual values meet engineering accuracy requirements, verifying the method’s reliability for characterizing temperature effects, guiding unstrained cable design, and implementing construction temperature compensation.