Sustainability is one of the main concerns in the textile industry. To address this issue, three-dimensional spacer fabric bra cups are developed by using fully fashioned knitting to reduce the production of waste. Five bra cups with different types of surface yarn and shapes are proposed. The physical and compression properties of the bra cups, degree of support and subjective sensation of the resultant bra prototypes are then evaluated and compared with a conventional daily wear bra with foam cups. The results show that the proposed bra cups could provide a compression strength and support comparable to those of foam bra cups but with air resistance decreased from 0.32 kPa･sec/m to<0.23 kPa･sec/m. The spacer fabric knitted bra cups made of double strands of surface yarn can exert significantly higher bra-skin interfacial pressure (p < 0.05) and reduce 9% of relative nipple displacement than that made of single strands of yarn. The different cup shapes show differences in perceived breast stability, gap between the breast and bra cup and thermal sensation. The outcomes show the feasibility of producing bra cups from yarn in one step and provide a reference for future development of sustainable intimate apparel.