The International Maritime Organization (IMO) sets ambitious greenhouse gas reduction targets for the maritime industry. From a long-term net zero emission perspective, ammonia fuel is expected to play a significant role in the marine decarbonization journey compared to LNG as a transition fuel. Also, in addition to internal combustion engine applications, solid oxide fuel cells (SOFCs) have gained more attention in marine propulsion applications due to their high efficiency. This study was performed to investigate the technical feasibility of utilizing a closed-loop SOFC thermal energy release for ammonia decomposition, leading to hydrogen fuel generation and subsequently feed back into SOFCs. The result proves that the integrated system of ammonia cracking SOFCs can maintain a self-balanced condition, ensuring adequate SOFC heat supply for the ammonia cracking process to produce hydrogen while supporting normal SOFC operation and generating heat. This paper concludes that an integrated system represents a novel and feasible solution and emphasizes its potential as an adaptable solution for future marine applications.