There are racial and ethnic inequities in exclusionary school discipline (ESD) (ie, a disciplinary action that removes students from their classroom or school environment, eg, referrals, suspensions, and/or expulsions) practices in the US. Exclusionary school discipline has been associated with negative education, health, and criminal justice outcomes. To investigate whether experiencing an ESD event was associated with decreased grade point average (GPA) and whether minoritized students (eg, Black or Latine [description used in database]) are disproportionately affected compared with White students. In a cohort study using retrospective administrative longitudinal data of children in the 6th to 10th grades (August 18, 2014, to May 26, 2017) in a large, single urban school district in California, linear mixed models were applied to compare the timing of the first exclusionary event and the average change in GPA and evaluate the relative variation among minoritized students experiencing an exclusionary event. Data analysis was conducted from August 18, 2018, to August 21, 2023. Year at which students experienced first ESD events over the study period. The primary outcome of interest was change in average grade point average (GPA); students' GPA averaged across courses was averaged across each year. Of the 16 849 students (8756 [52.0%] male), 21.4% experienced at least 1 ESD event. The mean (SD) age was 14.3 (1.6) years, and 7.5% identified as Black, 25.6% Latine, and 10.0% White. Black and Latine students experienced exclusionary events at nearly 10 and 3 times more than White students (mean [SD]: Black, 6.69 [12.80] events; Latine, 2.01 [6.18] events; White, 0.71 [4.46] events; P < .001). When controlling for gender, maternal educational level, race and ethnicity, and school year, having experienced an ESD event in the first year was associated with an average decrease in GPA by 0.88 (95% CI, -0.91 to -0.84) points compared with no ESD events; experiencing ESD events also had significant differences in the second (-0.63 [95% CI, -0.67 to -0.59]) and third (-0.52 [95% CI, -0.57 to -0.47]) years. Black and Latine race and ethnicity was associated with the greatest decrease in GPA compared with White students (Black, -0.56 [95% CI, -0.61 to -0.51]; Latine, -0.51 [95% CI, -0.54 to -0.47]; P < .001). This study observed racial and ethnic inequities in ESD prevalence and its association with educational attainment. The findings suggest that it may be beneficial for pediatricians and other health care professionals to screen for exclusion, as experiencing ESD events may affect health across the life course. In addition, it may be useful to categorize ESD events as an adverse childhood experience and abolish the practice from schools as a disciplinary measure.