This work reports the development of a MoS2@MWCNTs core–shell heterostructure synthesized through an optimized hydrothermal process, designed to enhance the oxygen evolution reaction (OER) efficiency in alkaline water electrolysis. By employing continuous tumbling during synthesis, a uniform and precise thickness of MoS2 was grown on the MWCNTs, striking a balance between maximal catalytic activity at the MoS2 edges, and leveraging the high electrical conductivity of the MWCNTs. The resulting MoS2@MWCNTs catalyst exhibited outstanding electrocatalytic performance for OER, with low overpotential of 285 mV at current density of 10 mA·cm−2, Tafel slope of 42 mV·dec−1, and exceptional durability, maintaining stable operation over 900 hours. Furthermore, the catalyst demonstrated robust performance under dynamic and unstable operating conditions, highlighting its potential for real-world applications in green hydrogen production. This study showcases the successful application of a core–shell structure for OER catalysis, while contributing to the advancement of sustainable energy technologies by providing a cost-effective and efficient solution for hydrogen production through water electrolysis.