Abstract: Teenage pregnancies and parenting are still major global concerns. In developing regions, there were reportedly 21 million teenage girls aged between 15 and 19 years who conceived in 2016, with 12 million of those pregnancies ending in live births. This study investigated the influence of psychological constructs on postpartum depression among breastfeeding teenagers in Kiambu County, Kenya. The objectives were; to find out the effect of life satisfaction on postpartum depression, to find the influence of family support on postpartum and to find the effect of self-awareness on postpartum depression. The study was guided by the hormone and cognitive theories. The study design was quantitative in nature. The study employed a cross-sectional research design. The target population was 10,382 teenage mothers who are currently breastfeeding. Participants were selected using random sampling to get a sample size of 385 teenage mothers who are breastfeeding. To gather primary data for this project, questionnaires were used. The study concluded that Based on the findings, it shows that life satisfaction has a significant influence on postpartum depression among breastfeeding teenagers. Higher levels of life satisfaction, including satisfaction in marriage/relationship, family treatment, societal treatment, and overall quality of life, are associated with a lower risk of postpartum depression. The study findings indicate that a strong family support plays a crucial role in reducing the risk of postpartum depression among breastfeeding teenagers. Positive family support, including emotional, practical and paternal support, is associated with lower levels of postpartum depression. The study findings indicate that higher levels of self-awareness contribute to a reduced risk of postpartum depression among breastfeeding teenagers.