BACKGROUND: Previous research has shown a high prevalence of violence among young people in Kenya. Violence is a known risk factor for HIV acquisition and these two public health issues could be viewed as a syndemic. In 2010, Kenya became the third country to implement the Violence Against Children and Youth Survey (VACS). The study found a high prevalence of violence in the country. Led by the Government of Kenya, stakeholders implemented several prevention and response strategies to reduce violence. In 2019, Kenya implemented a second VACS. This study examines the changes in violence and risk factors for violence and HIV between 2010 and 2019. METHODS: The 2010 and 2019 VACS used a similar sampling approach and measures. Both VACS were cross-sectional national household surveys of young people aged 13-24 years, designed to produce national estimates of physical, sexual, and emotional violence. Prevalence and changes in lifetime experiences of violence and risk factors for violence and HIV were estimated. The VACS uses a three-stage cluster sampling approach with random selection of enumeration areas as the first stage, households as the second stage, and an eligible participant from the selected household as the third stage. The VACS questionnaire contains sections on demographics, risk and protective factors, violence victimisation, violence perpetration, sexual behaviour, HIV testing and services, violence service knowledge and uptake, and health outcomes. For this study, the main outcome variables were violence victimisation, context of violence, and risk factors for violence. All analyses were done with the entire sample of 13-24-year-olds stratified by sex and survey year. FINDINGS: The prevalence of lifetime sexual, physical, and emotional violence significantly declined in 2019 compared with 2010, including unwanted sexual touching, for both females and males. Experience of pressured and forced sex among females also decreased between the surveys. Additionally, significantly more females sought and received services for sexual violence and significantly more males knew of a place to seek help in 2019 than in 2010. The prevalence of several risk factors for violence and HIV also declined, including infrequent condom use, endorsement of inequitable gender norms, endorsement of norms justifying wife beating, and never testing for HIV. INTERPRETATION: Kenya observed significant declines in the prevalence of lifetime violence and some risk factors for violence and HIV, and improvements in some service seeking indicators between 2010 and 2019. Continued prioritisation of preventing and responding to violence in Kenya could contribute to further reductions in violence and its negative outcomes. Other countries in the region that have made substantial investments and implemented similar violence prevention programmes could use repeat VACS data to monitor violence and related outcomes over time. FUNDING: None.