Living with breast cancer and experiencing a wide range of issues necessitates supportive care (SC). SC provides the necessary services for those affected by cancer to meet their physical, psychological, informational, practical, and spiritual needs. Therefore, this study's objectives were to identify the SCN of women undergoing breast cancer treatments and identify the predictors of SCN. A descriptive quantitative design was used using a convenience sample of 289 women with breast cancer drawn from the two largest cancer centers in Amman city. SCNs were measured using the Supportive Care Needs Survey Short Form (SCNS-SF -34). The reported needs were mainly within the following domains: informational (Mean, 34.07, SD = 8.91), physical (Mean = 16.85, SD = 4.74, and psychological (Mean = 28.49, SD = 7.20). Results also showed that SCN was influenced by the participants' education (R = 0.395), stage of illness (R2 = 0.156), and functional status (R2 = 0.129), produced at (F = 10.73 and P ≤ .001). It indicated that 16% of the variance in the needs of women with breast cancer could be predicted by stage, education, and the functional status of the women. In conclusion, a routine and systematic assessment of the SCN, social support, available resources such as trained clinical nurse specialists, and access to information is recommended to provide appropriate support.