Palaeozoic ophiolites are rare in the south-eastern Central Asian Orogenic Belt (CAOB) and are genetically significant for understanding the formation, evolution, and closure processes of the Palaeo-Asian Ocean (PAO). The Faku ophiolite is located in north Liaoning, NE China, and is dominated by the south-eastern CAOB within the Songliao Basin. It consists of several discontinuous tectonic blocks made up of serpentinised ultramafic rocks, gabbros, basalts, high-Mg andesites, marine and continental sedimentary formations, which are intruded by younger granites. We characterize the geochronology and geochemistry of the ophiolite. The ophiolite and granitic rocks have restricted εNd(t) (+2.60 to +6.08) and εNd(t) (+0.42 to +1.66). Zircons from the ophiolite and granite yielded weighted mean 206Pb/238U ages of 369–249 Ma and ca. 248.2 Ma, respectively, that we interpret as their crystallization (eruption) times. The ophiolitic rocks have a resemblance to enriched mid-ocean ridge basalts and within-plate basalts in terms of geochemistry, thereby representing a back-arc-type tectonic setting. The granite geochemically belongs to I-type, and formed in a syn-collisional orogenic environment. The sandstones from marine sediments are enriched with light rare earth elements and have low contents of SiO2 and MgO, and a positive zircon ɛHf(t) value indicating the affinities similar to those of ophiolitic rocks. The provenance of molasse is from the Baijiagou granites suggesting that the post-collisional orogeny and uplift occurred after the Early Triassic. We speculate that a juvenile intra-continental back-arc oceanic basin, which represents the southern affiliated branch of the PAO, might have formed by the continuous extension in southern CAOB since the late Devonian, and ultimately closed in the Early Triassic.