Rising sea levels and intensified storm events are accelerating coastal erosion and flooding, posing a significant threat to millions worldwide (including Australia). Traditional coastal defences, such as seawalls, are costly, environmentally disruptive, and require frequent upgrades as sea levels rise. Nature-based solutions, such as mangrove forests, offer sustainable alternatives by attenuating waves, stabilizing sediments, and sequestering carbon. However, establishing these protective habitats is often challenging due to the loss of emergent traits essential for their long-term persistence. This research investigates hybrid living shorelines by quantifying the hydrodynamic thresholds required for mangrove establishment and survival. Through wave hydrodynamic modelling (XBeach) of two rivers in New South Wales—the Hastings River and the Manning River—this study aims to optimize habitat rehabilitation and develop technical guidelines for designing effective hybrid solutions. The study contributes to climate adaptation strategies and provides support to cost-effective and ecologically sustainable coastal protection.