Background: Breast cancer is one of the leading causes of mortality among women in the world today. Therefore there is need for concerted efforts to advance interventions that seek to mitigate challenges associated with its screening. In Kenya, breast cancer accounts for 23% of cancerous diseases that affect women. The purpose of this study was to determine the knowledge levels on breast cancer among women of reproductive age in Kitui County, roll out community based health education intervention (CBHI) targeted at enhancing breast cancer knowledge, and finally to assess the effect of the CBHI on knowledge levels. Methods: The study design adopted was quasi-experimental. This was adopted because it enables researchers to evaluate causal relationships when interventions or agents of causation are induced. This study was undertaken with the causal mechanism being the rollout of CBHI and the impact in knowledge of breast cancer. Two groups were evaluated; intervention and control groups. The knowledge among these groups was evaluated between two time intervals; end line and at baseline. Data was collected using questionnaire instruments, analyzed using SPSS v23 and presented in form of tables and frequencies. Inferential analysis was achieved through binary logistic regression and Difference in Difference scores. Results: The individual score analysis on different aspect of breast cancer knowledge and awareness indicated that there was a direct positive impact of the CBHI on the knowledge on breast cancer among the respondents. Significant changes observed upon the implementation of CBHI on breast cancer included; respondents in the intervention group who knew at least two danger signs for breast cancer increased to 3.8 (Adj. OR=3.895, P<0.05, 95%CI: 2.538-5.979), those who knew the age related risks associated with breast cancer increased by 4.1 (Adj. OR=4.128, P<0.05, 95%CI: 2.940-5.797), and finally, those who knew at least one Breast cancer screening method increased 7 fold among the intervention group after the rollout of CBHI (Adj. OR=7.011, P<0.05, 95%CI: 4.138-11.880). Conclusion: The impact of CBHI on knowledge of breast cancer was significant. As a result, more people in the intervention group were cognizant of different warning signs of breast cancer, breast cancer screening methods, and that these opportunities facilitate early detection of breast cancer. The actionable strategies recommended by this study is implementation of community based strategies to enhance knowledge levels on breast cancer in order to improve screening uptake and therefore early detection of breast cancer.