We report the facile preparation of micro-nanostructured hybrids of Mg(BH4)2-carbon nanotubes (denoted as MBH-CNTs) and their enhanced hydrogen desorption/absorption performance. The hybrids with Mg(BH4)2 loadings of 25 wt%, 50 wt% and 75 wt% are synthesized through a one-step solvent method by adjusting the ratios of Mg(BH4)2 and CNTs. The optimized MBH-CNTs with 50 wt% Mg(BH4)2 exhibit a nanosized layer coating of Mg(BH4)2 with the thickness of 2-6 nm on the surface of CNTs. The MBH-CNTs with 50 wt% Mg(BH4)2 start to release hydrogen at 76 °C, which shows a significant decrease of about 200 °C compared with that of pure Mg(BH4)2 (about 292 °C). Furthermore, 3.79 wt% of H2 can be desorbed from this sample within 10 min at the peak release temperature of 117 °C. Meanwhile, the dehydrogenated MBH-CNTs could take up 2.5 wt% of H2 at 350 °C under the hydrogen pressure of 10 MPa. The high chemical activity of nanosized Mg(BH4)2 and the catalytic effect of CNTs synergistically promote reversible hydrogen storage. The simple synthesis process and enhanced hydrogen desorption/absorption of MBH-CNT hybrids shed light on the utilization of Mg(BH4)2 on CNTs as efficient hydrogen storage materials.