Maraging steels exhibit high ultimate tensile strength (UTS) and fracture toughness, but the key disadvantage is poor corrosion resistance. Ni, Cd and Cr coatings were applied additionally on the maraging steels to enhance corrosion resistance. However, using such coatings is hazardous to the environment. Through our present effort a precipitation-hardened (PH) martensitic steel has been indigenously developed with the inbuilt stainless property. PH martensitic stainless steels (MSS) offer optimum combinations of a high UTS, fracture toughness, corrosion resistance and stress corrosion cracking (SSC) resistance. These attractive properties render PH martensitic steels potential for structural applications in space, aerospace, defence, marine, and automotive industries. The present work investigates the effect of aging temperature (900, 950, 1100 and 1150°F with a fixed aging time (4 h)) and the effect of aging time (2-24 h) at 950°F on the formation of reverted austenite and Ni₃Ti precipitation and their correlation with mechanical properties of an indigenously developed PH MSS after solutionizing, water quenching and cryo treatment. X-Ray Diffraction analysis and electron backscattered diffraction scans of the cryo-treated samples showed no sign of retained austenite. Transmission electron microscopy based investigation of the cryo-cooled specimen revealed dislocation-rich lath martensite. With the increase in aging temperature, reverted austenite content at room temperature first increased with rapid kinetics of Ni partitioning. Later, the amount of reverted austenite found at room temperature decreased, which can be attributed to the instability of austenite formed at higher aging temperature, leading to its transformation to martensite during cooling. In contrast, the austenite content initially increased and then saturated with increasing aging time at 950°F. The ɳ-Ni₃Ti precipitates formed at the early stage of aging were found to have coarsened with aging temperature and time. Aging at 950 °F for 4 h rendered the best combination of UTS and ductility. The strength and microhardness rapidly increased to a peak value at the early stage of aging, then continuously decreased on further aging. Similar trend was obtained with respect to aging temperature also. These were in line with the early stage precipitation, followed by its coarsening. Ductility was influenced by the content of reverted austenite. The present work finds great utility in designing optimum heat treatment conditions for best combination of mechanical properties of this newly developed PH MSS for various space and aerospace applications.