<p>The production of metals, composites, and ceramics relies heavily on high-temperature processes. The development of refractory ceramics has significantly advanced the growth of key high-temperature dependent industries, including glass, iron and steel, nonferrous, petrochemical, and metallurgical sectors. Unreinforced refractory ceramics, however, suffer from low fracture toughness and inherent brittleness, limiting their structural applications. To mitigate these drawbacks, sintering additives have been used to produce reinforced mullite-refractory ceramics, with tailored microstructural morphology and enhanced mechanical properties for improved performance. This is achieved through compactness enhancement, porosity reduction, and the production of interlocked mullite fibers within the matrix, significantly improving densification, strength, and overall physico-mechanical properties. This review summarizes the effects of additives on the morphology and physico-mechanical properties of various mullite-based refractories, while highlighting the optimal processing conditions for maximizing refractory properties. Additionally, the directions for future development of high-performance mullite refractory ceramics have been highlighted.</p>