Deep-sea offshore wind power is crucial for reducing emissions in certain regions’ energy transitions. However, its development has been largely overlooked due to its high investment costs and fluctuation. Ammonia production offers a significant opportunity to enhance economic feasibility and facilitate energy consumption. This study, using a bottom-up model and based on the energy system of Fujian Province, China, examines the technical pathways for offshore wind-to-ammonia production. Through extensive scenario calculations, the study analyzes economic factors affecting the development of DOWD. The results show that when ammonia prices range from USD 0.52 to USD 0.6/kg, the deep-sea offshore wind with ammonia production (DOWD+AP) mode demonstrates its advantages, while the price of a single DOWD unit must fall below USD 1.73/W to show superiority. It is recommended that the installation of DOWD in Fujian province should not begin before 2040, with potential ammonia production capacity reaching 24 Mt/year. If ammonia production is unrestricted, the DOWD+AP mode could introduce a new method for flexible regulation, primarily compensating for gaps in solar- and wind-power generation during the summer months.