This case study aims to present the application of the Unified Protocol (UP) for the Transdiagnostic Treatment of Emotional Disorders in the case of a 38-year-old pregnant woman with a peripartum onset of major depressive disorder and anxiety symptoms. The UP is a cognitive-behavioral intervention based on the shared etiological and maintenance mechanisms of emotional disorders (i.e., mood, anxiety, and related disorders). The UP helps to modify maladaptive emotion-regulation strategies and enhance tolerance of unpleasant and intense emotions (sadness, anxiety, anger, etc.). Whereas previous studies demonstrate the efficacy of the UP in different emotional disorders, to our knowledge, none of them have used the UP to treat perinatal emotional disorders. After the eight UP modules of individual treatment, a significant decrease in anxiety, depression, negative affect, and anxiety sensitivity, and also an increase in positive affect were observed. These results were maintained at the 12-month follow-up. In addition to its clinical utility and acceptance, these results indicate that the UP can be adapted and personalized for the treatment of perinatal emotional disorders. Future studies with larger samples and controlled experimental designs should be developed to demonstrate its efficacy. Furthermore, as the UP seems to be useful in a group format, future efforts should be focused on the UP with perinatal women in a group format.