Immigrant populations continue to grow across Western countries. Such populations may face vulnerabilities that contribute to the risk of experiencing violent injury. Youths are at disproportionate risk compared with other age groups, and such violence may be preventable with appropriately targeted injury prevention strategies. To examine the association of immigrant or refugee status and immigration-related factors with the experience of assault. This population-based cohort study used linked health and administrative databases in Ontario, Canada, where health services are funded through a universal, single-payer health insurance plan. All youths and young adults aged 10 to 24 years (hereafter referred to as youths) residing in Ontario from January 1, 2008, to December 31, 2016, were eligible to participate. Data were analyzed from April 13, 2017, to January 6, 2020. The main exposure was immigrant status. Secondary exposures were immigration-related factors, including visa class, time since immigration, and region and country of origin. The main outcome consisted of violent injuries requiring acute care (emergency department visit or hospitalization) or causing death. Poisson regression models were used to estimate rate ratios for injuries. A total of 22 969 443 person-years were included in the analysis (51.3% male and 48.7% female participants). Compared with nonimmigrants, a greater proportion of immigrants lived in the lowest neighborhood income quintile (30.5% vs 18.2%) and urban areas (98.9% vs 87.7%). Among immigrants, 17.9% were refugees. Rates of violent injuries experienced were 549.0 (95% CI, 545.7-552.2) per 100 000 person-years in nonimmigrant youth, 225.0 (95% CI, 219.4-230.7) per 100 000 person-years in nonrefugee immigrant youth, and 525.4 (95% CI, 507.2-544.1) per 100 000 person-years in refugee immigrant youth. The rates of violent injury among nonrefugee and refugee immigrants were lower than among nonimmigrants (nonrefugee adjusted rate ratio [aRR], 0.41 [95% CI, 0.38-0.43]; refugee aRR, 0.82 [95% CI, 0.76-0.89]). Older age (oldest vs youngest aRR, 6.90 [95% CI, 6.53-7.29]), male sex (aRR, 2.60 [95% CI, 2.52-2.68]), and low neighborhood income (aRR, 2.42 [95% CI, 2.32-2.53]) were associated with violent injury risk. Rates of experiencing assault were lowest among South Asian (aRR, 0.33 [95% CI, 0.30-0.37]) and East Asian (aRR, 0.23 [95% CI, 0.19-0.26]) immigrants. Only Somali immigrants experienced higher assault rates (712.0 [95% CI, 639.3-805.3] per 100 000 person-years) compared with nonimmigrants. Most injuries (79.9%) were from being struck, followed by being cut (5.9%). The low rates of assault experienced by immigrants, including refugees, compared with nonimmigrants suggests that Canadian immigrant settlement supports and cultural factors may be protective against the risk of experiencing assault.