This study investigates the effects of annealing and annealing temperature on the temperature-dependent coefficient of thermal expansion (CTE) for two advanced materials: sintered Al–Si–Ni alloy and Al–TiC composite with in situ synthesized carbide particles. The experiments reveal significant differences in the annealing impact on the CTE behaviour of these materials. For the Al–TiC composite, the CTE demonstrates an Arrhenius-type dependence on temperature, with annealing causing a consistent reduction in CTE across the studied temperature range. While the activation energy associated with the Arrhenius-type dependence remains unaffected largely, the pre-exponential factor is altered significantly, pointing to structural and micro-structural transformations. XRD analysis confirms that increasing the annealing temperature decreases the crystallite size, particularly, in the carbide phase, that correlates with the observed CTE reduction. In contrast, the Al–Si–Ni alloy exhibits a more complex response to annealing. Annealing at 420°C increases slightly the CTE at higher measuring temperatures (> 100°C), while annealing at 550°C causes a notable rise in CTE at lower temperatures and leads to more stable, nearly linear temperature dependence. Crystallite size in the alloy increases with annealing, aligning with the observed rise in CTE. These findings highlight the critical role of microstructural changes induced by annealing in controlling the thermal-expansion properties of Al-based alloys. Understanding these mechanisms offers valuable insights for tailoring material performance in applications requiring precise thermal stability.