Here we report a new occurrence of ultrahigh temperature (UHT) granulites with a peak assemblage of sapphirine + quartz from the Sipiwesk Lake area of the Pikwitonei Granulite Domain (PGD), a Neoarchean high-grade metamorphic domain located at the northwestern margin of the Superior Province, Canada. Petrographic examination reveals that these UHT sapphirine + quartz granulites underwent three metamorphic stages: the prograde metamorphic stage is represented by the early remnant mineral assemblage of garnet, corundum, biotite, sillimanite, and K-feldspar inclusions within sapphirine and/or orthopyroxene; the peak metamorphic stage is marked by the typical UHT mineral assemblages of sapphirine + quartz and sapphirine + orthopyroxene; the retrograde stage is charactered by the matrix minerals of biotite, cordierite, and sillimanite. These mineral assemblages and their P-T estimates based on phase equilibria modelling constructed in NCKFMASHTO system define a clockwise P-T path involving an isobaric cooling process, suggesting a UHT metamorphism at the P-T condition of 1035-1110ºC and 7.9-9.0 kbar. The SHRIMP U-Pb dating on the metamorphic zircons yielded a weighted mean 207Pb/206Pb age at 2681 ± 13 Ma, interpreted to be the timing of the UHT event in the PGD. Combined with P-T paths and available metamorphic age data, this UHT event is considered to in connection with collision during the amalgamation of the Superior Province, generating at ~2.68 Ga by the upwelling asthenosphere due to slab break-off during this amalgamation.