Background: Antimicrobial resistance, driven by inappropriate and overuse of antibiotics, is a major public health threat. Diarrhea and respiratory illness are the leading causes of pediatric healthcare visits in low- and middle-income countries like Bangladesh. Despite clear WHO guidelines recommending limited use of antibiotics for these conditions, misuse is widespread. Methods: We interviewed caregivers of 3025 under-5 children via cellphones to assess common illnesses, associated care-seeking practices, and antibiotic use for diarrhea and respiratory illnesses experienced by their children in prior 14 days. Results: Among the participants, 116 (8.83%) reported diarrheal disease and 570 (18.84%) experienced respiratory illness during the preceding 2-week recall period. Among the children with diarrhea, 52.59% received antibiotics, and 73.77% obtained them over-the-counter from pharmacies. Among those with respiratory illness, 26.32% received antibiotics, with 58% procured them from local drugstores without a prescription from a registered physician. For diarrhea, azithromycin and metronidazole were the commonly used antibiotics; while for respiratory illness cefixime and azithromycin were frequently used. Notably, 68% of the diarrheal children either sought care from local drugstores, self-medicated, or did not receive any formal treatment. Conventional practice, long wait times at healthcare facilities, distance, and poverty were the main reasons for not seeking care from a registered healthcare provider. Conclusion: Understanding community-level antibiotic use and care-seeking behavior is essential to strengthen antibiotic stewardship and child health programs. Our findings highlight the urgent need for community awareness and enforcement of regulations restricting the over-the-counter sale of antibiotics to curb irrational and excessive antibiotic use.