This chapter reviews the importance of oilseeds, particularly Brassica napus, Brassica juncea, Brassica rapa, and Brassica carinata in the global agricultural economy, as they are the channels of vegetable oil and protein sources popular with people and livestock. Their contributions toward food security have, therefore, increased and continue to increase as demand increases worldwide because of the improved yields through breeding and agronomic innovations. This chapter gives information on the nutritional composition of each species regarding some important minerals, beneficial fatty acids, and bioactive compounds, including flavonoids, tocopherols, and glucosinolates, toward their health-promoting properties. Brassica napus would offer the best oil content along with a profile favorable in fatty acids, while Brassica rapa is rich in omega-3 fatty acids. Antioxidant and anti-inflammatory properties are shown by Brassica juncea, which is attributed to the significant bioactive constituents present in its oil. Another key advancement is seen in Brassica carinata as a prospect for biofuels. In addition, global oilseed market trends are discussed, along with factors such as population increase and changing consumer preferences that contribute to the growing demand for plant-based oils. Emerging economies are expected to drive a substantial portion of the growth in this market. Therefore, it is essential to know these trends and their relationship with the nutritional quality of Brassica oilseeds, given that they offer opportunities that can be exploited for achieving food security and improving agricultural growth in the rapidly evolving oilseed sector.