Background <p>Functionally graded materials offer critical advantages in thermal resilience for advanced engineering. Analyzing the thermo-mechanical behavior of spherical nanoshells is essential for micro/nano-electromechanical systems safety.</p> Purpose <p>This study aims to analyze the thermo-mechanical response of a functionally graded spherical nanoshell under ramp-type thermal load using a new fractional-order three-phase-lag model with nonlocal effect.</p> Methods <p>Closed-form solutions for temperature, displacement, radial stress and hoop stress are derived analytically using the Laplace transform and its inverse.</p> Results <p>Parametric analysis shows the ramp-heating, fractional-order and nonlocal parameters significantly influence wave propagation and thermo-mechanical responses at micro/nano-scale.</p> Conclusion <p>The model and results provide a reference for accurate thermo-mechanical design of functionally graded nanostructures in advanced micro/nano-electromechanical systems.</p>