Introduction: One of the most widely used instruments to identify symptoms that may be related to central sensitization is the Central Sensitization Inventory (CSI). Although this instrument has been translated and validated in Spanish patients with chronic musculoskeletal pain, no psychometric analysis has been carried out in breast cancer survivors. The aim of this study was to perform a psychometric analysis of the Spanish version of the Central Sensitization Inventory (CSI-Sp) in Spanish breast cancer survivors. Materials and Methods: A validation study was carried out in 183 breast cancer survivors. A psychometric analysis of internal consistency, factor structure, and test-retest reliability of the CSI-Sp was performed. Internal consistency was determined using Cronbach’s alpha. Test-retest reliability was evaluated using the Intraclass Correlation Coefficient (ICC) Type 2.1. Exploratory factor analysis was used to determine the internal structure of the questionnaire. Results: The internal consistency was high (α = 0.91). The test-retest reliability was satisfactory with excellent values (ICC 2.1 = 0.95). The exploratory factor analysis yielded a one factor structure explaining the 33.88% of total variance. Conclusions: The CSI-Sp has demonstrated to be a psychometrically strong measure for assessing central sensitization symptoms in breast cancer survivors based on internal consistency, test-retest reliability, and structural validity. Further studies that analyze other measurement properties in different Spanish clinical populations are needed.