We have uncovered evidence of Neoarchean ultrahigh-temperature (UHT) metamorphism in the Karimnagar Granulite Terrane (KGT), southern India, based on new petrological and mineralogical data of sapphirine-bearing and related granulites. We investigated their petrogenesis and implications of a hot orogen along the north-eastern margin of the Eastern Dharwar Craton (EDC). We found various reaction textures, such as spinel mantled by sapphirine and hydration of orthopyroxene, indicating a peak mineral assemblage of cordierite + sapphirine + spinel + orthopyroxene + biotite + rutile + K-feldspar. Phase-equilibria modelling in the Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–Fe2O3 system indicates peak metamorphic conditions of 905 °C–910 °C and 4.5–4.6 kbar. The peak stage was followed by a retrograde metamorphic stage represented by increasing modal abundance of biotite and consumption of rutile and spinel at ~730 °C and ~ 4 kbar, suggesting near-isobaric cooling. Using the chemical Th–U-Pbtotal isochron method, we dated monazites in textural association with sapphirines and cordierites in a sapphirine–spinel–orthopyroxene–cordierite granulite. The resulting Neoarchean age (2638 ± 44 Ma) probably represents the timing of peak UHT metamorphism. We infer that Neoarchean UHT metamorphism and post-peak near-isobaric cooling took place in the terrane during the terminal stage of complex accretion–collision tectonic processes related to amalgamation of microcontinents and/or magmatic arcs that occurred during 2.70–2.62 Ga, one of the major episodic crust-forming events in the EDC. Our findings and regional distribution of lithologies overturn the existing tectonic model of the KGT as a collisional suture zone between the EDC and the Bastar Craton. Moreover, we propose that the KGT is a discrete tectonic block composed of ~2.7–2.6-Ga granulites and younger granite representing the mid-crustal segment of the EDC, which was uplifted as a tilted tectonic block along the southern flank of the Kadam outlier.