<p>In recent decades, hydrogen-induced damage in high-strength offshore steel has emerged as a significant challenge in marine engineering. This study investigates the effects of Nb-Ti microalloying on the microstructure and hydrogen-induced damage behavior of steel using microstructural characterization, internal friction, hydrogen permeation, slow strain rate tensile testing, and hydrogen-induced cracking. The results show that increasing Nb-Ti content in the steel significantly reduces the average grain size of prior austenite and the width of tempered martensite laths, thereby improving mechanical properties. More importantly, Nb-Ti addition increases the number of hydrogen traps, resulting in a notable reduction in hydrogen’s effective diffusion coefficient. Internal friction analysis reveals that after hydrogen charging, the activation energies of the C-SKK peak, grain boundary peak, and second-phase interface relaxation peak decrease, and a unique hydrogen-induced peak is observed. The increase in Nb-Ti content not only refines the microstructure but also promotes finer and more uniform distribution of precipitated phases, thereby enhancing the steel’s resistance to hydrogen-induced damage. Simultaneously, it improves the hydrogen-induced damage resistance of the tested steel without reducing its yield strength. It is proposed that Nb-Ti microalloying is a feasible way to further improve the comprehensive performance of high-strength steel for marine flexible risers.</p>