The Blue Economy is one of the emerging strong pillars of socioeconomic and ecological development and growth across the world. It is one of the few resource-base whose exploitation can be conducted sustainably, and also whose ecological protection can generate economic value. In 2020, the United Nations Economic Commission for Africa (UNECA) developed a Blue Economy Valuation Toolkit (BEVT). This toolkit allows countries to assess the economic, social, and ecological value (in quantitative terms) that BE resources generate. Equipped with this information, countries can strategize on how best to optimism on these BE resources for enhanced socioeconomic and ecological gains. The United Republic of Tanzania requested UNECA for support to conduct a domestication of the toolkit, with the aim to understand the value that its BE resources generate, in support of national growth and development. The BEVT was therefore applied to Mainland Tanzania, using the Supply Use Table data from 2015, obtained from the National Bureau of Statistics (NBS) of Mainland Tanzania. A tentative estimation of Zanzibar was also conducted, using data from the Supply Use Table 2015. The ecosystem valuation was done using a pool of data ranging from 2015 to 2020 sourced from National Environmental Research Agenda, 2017-2022.