Display omitted •Ternary NiCo/Mn/GO catalyst was rationally sysnthesized.•NiCo/Mn/GO exhibited excellent electron transport capability and PMS activation.•CIP degradation by NiCo/Mn/GO + PMS system occurred over different water conditions.•Radicals and non-radicals were involved in CIP degradation by NiCo/Mn/GO + PMS.•NiCo/Mn/GO was sustainable in multiple cycles of CIP degradation efficiency. A catalyst, NiCo2O4/MnOOH/GO, was successfully synthesized by immobilizing NiCo2O4 and graphene oxide (GO) on MnOOH for the activation of peroxymonosulfate (PMS) with enhanced catalytic activity in ciprofloxacin (CIP) degradation. Results demonstrated 99% removal of CIP (0.02 mM) in the NiCo/Mn/GO system after 30 min at 0.2 mM of PMS and 0.15 g/L of NiCo/Mn/GO. The effects of solution pH, catalyst dose, PMS concentration, major inorganic ions, and natural organic matter (NOM) on CIP degradation were studied. The NiCo/Mn/GO exhibited good sustainability in catalytic removal efficiency for multiple uses. Furthermore, scavenger tests and electron paramagnetic resonance (EPR) results showed that singlet oxygen (1O2), superoxide radicals (O2•-), sulfate radicals (SO4•−), and hydroxyl radicals (•OH) were generated in the NiCo/Mn/GO + PMS system and participated in CIP degradation. The NiCo/Mn/GO is a promising catalyst for PMS activation in the degradation of CIP and other emerging contaminants.