<p>Precipitation-hardened alloys demonstrate significant application potential in high-end industries such as aerospace, energy storage and conversion, power generation and automotive manufacturing, owing to the exceptional stability of their microstructures and the related mechanical properties up to high temperatures. With this, these materials offer important prospects and opportunities for enhancing the sustainability of materials in critical application fields. The secondary-phase particle coarsening in precipitation-hardened alloys was reviewed, systematically revisiting the Ostwald ripening mechanism and integrating the matrix diffusion-controlled Lifshitz–Slyozov–Wagner and trans-interface diffusion-controlled models to elucidate coarsening kinetics. Recent advances in understanding how temperature, aging time, volume fraction, shape factor, plastic strain, and alloying elements regulate coarsening behavior and influence alloy properties are comprehensively analyzed. The morphological evolution of precipitates and its effect on material service performance are discussed in detail. Strategies to inhibit coarsening, including alloy composition design (e.g., introducing slow-diffusing elements and thermally stable phases), processing technology (e.g., thermomechanical treatment and nanoparticle dispersion), and external condition control, are highlighted. The precise regulation of nanoparticulate size, development of advanced heat treatment processes, and in-depth exploration of the synergistic effects between plastic strain and interfacial energy will be pivotal for optimizing microstructures and extending the service life of precipitation-hardened alloys.</p>