Race-based discrimination represents an ongoing public health crisis in the US, manifested by wide-ranging disparities in youth health, mental health, and violence exposure. However, studies of racial discrimination often neglect experiences of identity-based bullying (IBB) stemming from other marginalized identities, such as gender identity and sexual orientation. To examine associations between experiences of IBB based on race/ethnicity/national origin and other social identities and youth health, mental health, and violence outcomes. This cross-sectional study analyzed responses from an anonymous survey conducted at 13 public high schools in Pittsburgh, Pennsylvania, between October 15, 2018, and October 19, 2018. Participants included in the study were in the 9th through 12th grades. Data were analyzed from October 15, 2020, to February 14, 2021. Experiences of bullying and bullying perpetration based on race/ethnicity/national origin and other social identities (ie, gender identity, sexual orientation, religion, physical or mental disability, immigration status, other unspecified reason). Youth health (delayed well care; forgone medical care; physical, mental, or emotional limitations), mental health (nonsuicidal self-injury, suicidal ideation), and violence involvement (weapon perpetration or survivorship, fighting, sexual assault, adolescent relationship abuse, experiencing homicide of friend or family member) were assessed using self-reported items modeled on the Centers for Disease Control and Prevention Youth Risk Behavior Survey. Among 3939 participants, the mean (SD) age was 15.7 (1.3) years; 1380 students (36.3%) identified as Black/African American, 2086 (53.7%) as assigned female at birth, 1021 (32.6%) as belonging to a sexual minority group, and 313 (10.0%) as gender diverse. Among reported social identities, race/ethnicity-based experiences of bullying (375 students [9.5%]) and bullying perpetration (209 students [5.8%]) were the most common. Youth with multiple stigmatized identities experienced even higher rates of experiences of IBB and IBB perpetration. Specifically, the highest rates of IBB were reported by gender diverse Black and Hispanic youth. Experiencing IBB based on multiple stigmatized identities was associated with all outcomes, including delayed well care (aOR, 1.41; 95% CI, 1.20-1.65), forgone medical care (aOR, 1.64; 95% CI, 1.44-1.87), nonsuicidal self-injury (aOR, 2.86; 95% CI, 2.53-3.24), suicidal ideation (aOR, 2.49; 95% CI, 2.20-2.83), and greater violence involvement (experiencing violence: aOR, 2.90; 95% CI, 2.45-3.43; homicide survivorship: aOR, 1.19; 95% CI, 1.06-1.33). These results further encourage the development of youth health, mental health, and violence prevention programs that address experiences of bullying based on multiple marginalized identities.