Background: Gender-based violence has a negative impact on the physical and mental health of the victim, especially younger adults. Methodology: This cross-sectional descriptive study was carried out in Cross River and Akwa Ibom States of Nigeria using both qualitative and quantitative approaches. The study population comprised young adults aged 15-39 years in Cross River and Akwa Ibom States. The principal researcher and three field assistants administered 426 copies of the questionnaire to respondents. The data were analyzed using Statistical Packages for the Social Sciences software (SPSS) version 22. Thematic analysis was used for the qualitative data. Results: The majority of respondents 346(83.8%) knew that gender-based violence affects the health and wellbeing of victims; there were 267(64.6%) young adults who identified that gender-based violence poses both long-term and short-term effects on the health of the victims with 198(47.9%) who have suffered at least, one form of gender-based violence. Shame, (32.7%), anger, (27.8%), Bruises/injuries (25.2%) and low self-esteem (22.5) were the most frequently reported physical and emotional health effects of GBV. Many do not seek care due to shame. For those who sought care, counseling 97(49%), HIV/AIDS counselling and screening 66 (33.3%), STI screening 52(26.2%), and oral pills 24(12.2%) were some of the services accessed by victims. Discussion: This finding is consistent with reports from other GBV studies whose respondents suffered depression (48.8%), fear and anxiety (31.0%), which they argued were more serious conditions than the physical health impact of gender-based violence. Mental and emotional health outcomes of GBV are mostly invisible to others, making it harder for victims to seek help. Conclusion: Gender-based violence has negative impact on the physical and mental health of the victim, especially younger adults.