A monolithic reactor with multi-jet-channel in the circumferential array (MR-MJCCA) is designed to intensify mass transfer. Effects of operating conditions and geometric parameters on the mass transfer efficiency E and overall volumetric mass transfer coefficient KLa are illustrated through experimental and numerical methods. Results show that the increased jet impingement intensity due to a higher flow rate and smaller jet diameter Dp effectively enhances mass transfer. E and KLa in the MR-MJCCA possessing eight channels increase with reducing the channel depth De and helical pitch p, yet first rise and then decline with enlarging the jet unaligned-impinging distance w. A higher two-phase interfacial area and energy dissipation rate are conducive to improving mass transfer performance in configurations with Dp = 0.3 mm, De = 1 mm, p = 5 mm, and w = 1.5 mm. Increasing the axial length of reactor elevates E whereas KLa diminishes. A reliable artificial neural network model was used to correlate KLa with key parameters. MR-MJCCA exhibits a higher KLa compared to most microreactors and the throughput increases by over tenfold, demonstrating its scalability and broader industrial applications.