The objective of this study is to propose an optimal plant design for blue hydrogen production aboard a liquefied natural gas (LNG) carrier. This investigation focuses on integrating two distinct processes—steam methane reforming (SMR) and ship-based carbon capture (SBCC). The first refers to the common practice used to obtain hydrogen from methane (often derived from natural gas), where steam reacts with methane to produce hydrogen and carbon dioxide (CO₂). The second refers to capturing the CO₂ generated during the SMR process on board ships. By capturing and storing the carbon emissions, the process significantly reduces its environmental impact, making the hydrogen production “blue,” as opposed to “grey” (which involves CO₂ emissions without capture). For the SMR process, the analysis reveals that increasing the reformer temperature enhances both the process performance and CO₂ emissions. Conversely, a higher steam-to-carbon (s/c) ratio reduces hydrogen yield, thereby decreasing thermal efficiency. The study also shows that preheating the air and boil-off gas (BOG) before they enter the combustion chamber boosts overall efficiency and curtails CO₂ emissions. In the SBCC process, pure monoethanolamine (MEA) is employed to capture the CO₂ generated by the exhaust gases from the SMR process. The results indicate that with a 90% CO₂ capture rate, the associated heat consumption amounts to 4.6 MJ per kilogram of CO₂ captured. This combined approach offers a viable pathway to produce blue hydrogen on LNG carriers while significantly reducing the carbon footprint.