Background: Sexualized substance use (SSU) is the practice of psychotropic substance usage, before or during sexual intercourse in order to increase sexual pleasure and arousal. It has a strong association with sexually transmitted infections (STIs). The present study aimed to assess the knowledge gaps regarding SSUs among the community health mobilizers by interviewing them regarding their knowledge, attitudes, and practices through qualitative approach. Methodology: In-depth interviews (IDIs) were conducted with a total of nineteen community health mobilizers engaged in counselling of sexualized substance users. A semi-structured open-ended questionnaire with socio-demographic information and probes related to SSU was administered. Informed consent was taken from each participant prior to data collection. Results: Gender-wise distribution indicated that 47% of the community mobilizers are men, followed by transgender persons (32%), and women (21%). Responses of participants highlighted that alcohol consumption was the most observed form of SSU. The findings indicated that drug administration through injection was most common, followed by sniffing and swallowing. Sources of drug pro-curement enlisted by participants included peddlers, peer groups, sexual parties, medical and liquor stores. Only 63% of participants had fair knowledge about STIs such as HIV, viral hepatitis, syphilis, and gonorrhoea. All were familiar with the administration of naloxone injections and the locations of nearby hospitals where patients could be transported in the event of an overdose. Conclusions: The in-depth interviews among the study participants reflected substantial know-ledge gaps related to various areas associated with SSU, which highlights the need for periodic workshops and training for upgradation of existing knowledge and practices among community health mobilizers. This will help to broaden their knowledge of different types of SSUs, the latest substances of abuse, the diseases caused by high-risk sexual practices, and additional health and psychological issues associated with SSUs, which would ultimately help in better counseling and management of sexualized substance users. It may also play a crucial role in the strengthening of capacity-building systems and engagements at the community level. This study may be used as formative research by researchers and policy makers to develop study protocols for multi-centric community-based studies among community health mobilizers and sexualized substance users across the country for further validation and exploration.