Many late Mesozoic granites within the Lower Yangtze River Belt (LYRB), eastern China, are defined as A-types based on their geochemical characteristics, although their petrogenesis is unclear. We present an integrated study combining geochronology, whole-rock geochemistry, Sr, Nd, Pb and zircon Hf isotopes and mineral chemistry for a lithologically-diverse suite of A-type granitoids at Bashan. The Bashan complex in the Chizhou area is composed of quartz monzonite, quartz syenite, syenogranite and alkali-feldspar granite. Zircon UPb geochronology indicates that these intrusive rocks formed at 126–123 Ma. The quartz monzonites have intermediate SiO₂ (60.5–63.1 wt%) and high Na₂O + K₂O (8.66–9.83 wt%) contents, arc-like trace element compositions, enriched whole-rock Sr, Nd and zircon Hf isotopes ((⁸⁷Sr/⁸⁶Sr)_i = 0.7082–0.7091; ε_Nd(t) = −6.9 to −7.1; ε_Hf(t) = −5.3 to −8.2) and high radiogenic Pb isotopes (²⁰⁶Pb/²⁰⁴Pb(t) = 18.581–18.792). They are inferred to have been derived from partial melting of an enriched lithospheric mantle source, followed by fractional crystallisation and limited crustal contamination. The quartz syenites show high SiO₂ (65.9–69.8 wt%) and Na₂O + K₂O (11.3–12.3 wt%) contents, low MgO (0.14–0.23 wt%) contents, high 10⁴ * Ga/Al (2.34–3.61) values, arc-like trace element compositions, and whole-rock Nd and Pb and zircon Hf isotopic compositions (ε_Nd(t) = −6.8 to −7.0; ε_Hf(t) = −7.3 to −12.3; ²⁰⁶Pb/²⁰⁴Pb(t) = 18.559–18.970) similar to the quartz monzonite, suggesting that they were derived through fractional crystallisation of the quartz monzonite, with some crustal assimilation. The quartz monzonite has higher Ti-in-zircon temperatures (T_Ti-in-Zrn = 696–832 °C) and lower zircon saturation temperatures (T_Zr = 772–818 °C) and oxygen fugacities (ΔFMQ = +1.8 to +2.8) than the quartz syenite (T_Ti-in-Zrn = 623–805 °C; T_Zr = 856–909 °C; ΔFMQ = +3.5 to +4.8), indicating that the zircons from the quartz syenite crystallised at lower temperatures, and that the oxygen fugacity significantly elevated as the magmatic temperature decreases. The syenogranites display high SiO₂ (74.6–75.5 wt%) contents, high T_Ti-in-Zrn (671–871 °C), T_Zr (799–822 °C), and low oxygen fugacities (ΔFMQ = +0.9 to +3.7), and thus did not evolve from the quartz syenite. They show high 10⁴ * Ga/Al values (2.67–2.95), low MgO (0.1–0.17 wt%) contents and (La/Yb)_N (7.60–10.19) ratios, pronounced negative Eu anomalies (Eu/Eu* = 0.28–0.38) and enriched Sr, Nd and zircon Hf isotopic compositions (ε_Nd(t) = −7.2 to −7.5; ε_Hf(t) = −5.1 to −14.0), indicating that they were derived from fluid-absent partial melting of Neoproterozoic calc-alkaline igneous rocks under low-pressure–high-temperature conditions. The alkali-feldspar granites are characterised by high SiO₂ (76.5–78.0 wt%) and Na₂O + K₂O (8.34–9.02 wt%) contents, but low MgO (0.03–0.08 wt%) contents. They show less enriched Nd isotopes (ε_Nd(t) = −5.7), a wide range of zircon ε_Hf(t) values (−1.9 to −11.2) and high oxygen fugacities (ΔFMQ = +2.9 to +4.3). They were produced by mixing of highly-fractionated alkaline basaltic magmas and melts derived from partial melting of Mesoproterozoic crust. The inferred petrogenesis of the Bashan complex magmatic rocks suggests that the A-type granites within the LYRB have multiple magmatic sources and crystallised under a wide range of temperatures, water contents and oxygen fugacities. During the Mesozoic, subduction and rollback of the Palaeo-Pacific slab induced crustal extension and intense crust–mantle interaction, which played a dominant role in the formation of the A-type granites within the LYRB.