Acute respiratory infections (ARIs) are the leading cause of infectious disease-related morbidity, hospitalization, and morbidity among children worldwide. This study aimed to assess the viral and bacterial causes of ARI morbidity and mortality in children under 5 years in Senegal. Nasopharyngeal samples were collected from children under 5 years who had ARI. Viruses and bacteria were identified using multiplex real-time reverse transcription-polymerase chain reaction and conventional biochemical techniques, respectively. Adenovirus was the most prevalent virus (50%; n = 81), followed by influenza virus (45.68%, n = 74), rhinovirus (40.12%; n = 65), enterovirus (25.31%; n = 41), and respiratory syncytial virus (16.05%; n = 26), whereas Streptococcus pneumoniae (17%; n = 29), Moraxella catarrhalis (15.43%; n = 25), and Haemophilus influenzae (8.02%; n = 13) were the most commonly isolated bacteria. Virus pathogens seem more likely to be more prevalent in our settings and were often associated with bacteria and S. pneumoniae (6%; 16) coinfection.