Globally, immunization coverage dropped from 86% in 2019 to 83% in 2020. An estimated 23 million children under one year did not receive basic vaccines, which is the highest number since 2009. Thus, this study aimed at identifying factors influencing the knowledge and attitude of mothers of under-five children towards immunization in Farato, The Gambia. A descriptive cross-sectional study was conducted in the peri-urban community of Farato. A sample of 132 mothers were conveniently sampled and interviewed using a structured questionnaire. Descriptive statistics such as percentages, frequencies, and proportions were used to present the results of this study. The study revealed a low level of knowledge of mothers towards immunization. About 25% of mothers cannot clearly explain immunization; 23% knew that the first vaccine dose should be administered to a child at birth or soon after, and 60% were found to be unaware if their children were immunized. This indicates that the concept of immunization is not even clear to mothers and also showcased inadequate knowledge. However, 70% highlighted that immunization prevents infections and enhances child survival. Inadequate knowledge about immunization, literacy and education level, occupation of mothers, inadequate information from health workers, and limited information among mothers were major influencing factors to drop-out of immunization uptake. The study suggests that mothers need to be taught what immunization is about and its importance to children. At health facilities and clinic sites, health workers need to continue communicating to mothers on the importance of immunization to enlighten them about immunization.