Background: The study aimed to explore the perception of mothers of adolescent girls and health service providers in urban slums toward HPV vaccination. Methodology: A cross-sectional mixed-method study in the slums of Rayer Bazaar, Kamlapur and Mohakhali was conducted. The quantitative part included a household survey of mothers (n=150) and service providers (n=30) through a semi-structured pre-tested questionnaire and qualitative interviews included in-depth interviews (IDI) with mothers (n=10) and key-informant interviews (KII) with service providers (n=10). Results: Around 96% of mothers had never heard of HPV, and 98% were unaware that the virus's transmission could be halted. Only 3.3% of mothers were aware that HPV can cause cervical cancer, although, during IDI, it was seen that the majority of mothers said that cervical cancer is a communicable disease. Nearly 98% of mothers wanted their daughters to get vaccinated. Service providers had a good understanding of HPV, HPV vaccine, and cervical cancer. All service providers during KII agreed that if they had received adequate training on HPV vaccination and cervical cancer, they could have treated their patients better. Conclusion: The findings of this study have important implications for the design and advocacy of HPV immunization programs in Bangladesh.