Utilising the metamorphic pressure–temperature–time (P–T–t) record through Earth’s history is a proven tool to investigate crustal processes and Earth’s evolving tectonic mode(s). In the Archean Eon, a fragmentary rock record before 2.8 Ga hinders our understanding of the early Earth. Here, we investigate well-preserved metabasic rocks from the northern Itsaq Gneiss Complex, southwest Greenland. We examine the P–T conditions of metamorphism via phase equilibrium modelling and link the results to geochronological constraints obtained via in-situ garnet Lu–Hf geochronology. The two studied garnet amphibolites record peak assemblages of amphibole + plagioclase + garnet + quartz ± biotite with accesory zircon, apatite ± ilmenite/titanite. Both samples record evidence for incipient partial melting as quartz and plagioclase pseudomorphs replacing former melt films along grain boundaries. Phase equilibrium modelling indicates peak metamorphic P–T conditions of ~8 kbar and 730–800 ºC. In-situ garnet Lu–Hf dates of 3.6–3.5 Ga are interpreted to reflect cooling ages, given the P–T modelling results and closure temperature for Lu–Hf in garnet of ca. 650 ºC for the analysed garnet grain sizes. The findings are interpreted to record granulite facies metamorphism attributable to the ca. 3.66–3.60 Ga Isukasian orogeny in the Itsaq Gneiss Complex.