INTRODUCTION: In less developed countries, including the Gambia, childhood diarrhea is one of the leading causes of serious illness and death among children. Studies on wider determinants of behaviors in medical treatment seeking for diarrheal illnesses in poor resource settings are limited. However, the challenges are continuing and, there is a gap in research work about it in the Gambia. Therefore, the rationale of this study was to assess the individual and community level factors of medical treatment-seeking behaviors for childhood diarrhea among mothers in the Gambia. METHODS: Data from the 2019-20 Gambia demographic and health survey were used in this study, which was based on secondary data analysis. A total of 1,403 weighted samples of under-five children's mothers were included in the study for diarrhea medical treatment-seeking behaviors. Because of the hierarchical nature of the data, a multi-level logistic regression model was applied to identify individual and community-level factors that may influence mothers' medical treatment-seeking behaviors of diarrhea. Data were analyzed using multilevel logistic regression analysis. In the multivariable multilevel logistic regression analysis, variables were judged significantly linked with medical treatment-seeking behavior of diarrhea if their p-value was less than 0. 05. RESULTS: Medical treatment-seeking behaviors for diarrhea were discovered in 62.24% (95% CI: 59.67,64.74) of mothers of under five children. Being a female child has shown odds of (AOR = 0.79, (CI 95%: (0.62,0.98)) times less treatment-seeking behavior than the counterparts. Moreover, compared to mothers whose children were of average size, those whose children were smaller, and larger than average at birth were more likely to seek out pediatric medical treatment (AOR = 1.53, 95% CI (1.08-2.16), and (AOR = 1.31, 95% CI (1.01,1.169)) respectively. On the other side, mothers who have exposure to listening to the radio, and heard about oral rehydration have shown an odds of (AOR = 1.34, CI 95%, (1.05,1.72)), (AOR = 2.21, CI 95%, (1.14,4.30)), being from the middle, and rich household wealth have also shown (AOR = 2.15, CI 95%, (1.32,3.51)), and (AOR = 1.92, (CI 95%, (1.11,3.32)), a child with cough, and fever (AOR = 1.44, CI 95%, (1.09,1.89)), and (AOR = 1.73, CI 95%, (1.33,2.25)) were individual-level factors that have shown association statistically with the outcome variable. Similarly, regarding community level factors mothers who had a postnatal checkup, and those from the Kerewan region have revealed more odds of (AOR = 1.48, CI 95%, (1.08,2.02)), and (AOR = 2.99, CI 95%, (1.32,6.78)) times significantly with treatment seeking behavior of mothers respectively. CONCLUSION: Diarrhea medical treatment-seeking behavior was found low. Hence, it remains among the top public health challenges in the Gambia. Strengthening mothers' healthcare-seeking behavior and skills on home remedies, and childhood illnesses, advocating mass media exposure, assisting financially disadvantaged mothers, and postnatal checkups after delivery will enhance medical treatment-seeking behavior. Furthermore, coordinating with regional states, and designing timely policies and interventions are highly advisable in the country.