Guinea-Bissau has recently become the fifth largest producer and exporter in the world of Cashew Nut Shell (CNS) and the product accounts for 90% of the country’s total exports. The objective of this study was to analyze the expansion of cashew cultivation and its environmental and economic impacts on the country, from the perspective of sustainable development. In the methodology, correlational statistical analyses were used, based on multiple regression, correlation, and linear regression techniques. To qualify the empirical results based on the historical series of secondary data, an online questionnaire was applied to nine experts to assess the impacts of sector-specific public policies on Cashew Nut Shell Production (CNSP) and Cashew Nut Shell Export (CNSE). Finally, geoprocessing techniques were used to identify the deforestation trends in the country (2002-2018). As main results, it was verified that from 2000 to 2015, the CNSE accounted for an average of 8.9% of the country’s GDP. As for environmental impacts, it was found that between 2002 and 2012, the country’s deforestation was explained by the CNSP (p < 0.001 and R² = 0.91), whereas between 2013 and 2017, although positively associated, the relationship was not significant. Geoprocessed data on vegetation cover indicate that from 2002 to 2018, accumulated deforestation was intensified mainly in the southern and northern regions of the country. To make full use of cashew, a greater effort is needed from the Government and the productive sectors, which would allow the sustainable development of the sector and a substantial increase in the production of other crops.