Background: As COVID-19 has let many students into remote learning environments and exacerbated inequality among marginalized individuals, there is a growing concern about Bias-Based Bullying (BBB) in online spaces among school-aged youths. Learning modality and perceived school fairness may affect youth's likelihood of reporting BBB. Methods: Data were collected as part of "No Place For Hate" (NPFH) project, which was conducted by an equity office of a school district. A sample of middle and high school students (N = 1117) in the school district was used as an analytic sample. We conducted a series of independent samples t tests and calculated a hierarchical stepwise multivariate regression model to examine the proposition. Results: Results demonstrated that students in fully remote modality reported slightly higher levels of witnessing BBB (t = 2.29, p < 0.05), lower perceived school fairness (t = -2.94, p < 0.01), and higher levels of likelihood of reporting BBB (t = 2.31, p < 0.05). Results of the regression model showed that perceived school fairness was positively associated with likelihood of reporting BBB, even when considering the influences of sociodemographic characteristics, learning modality, and experience of witnessing BBB. Conclusions: Findings of this study suggest that learning modality and perceived school fairness can meaningfully explain witnesses' likelihood of reporting BBB. Additional research should continue investigating how schools can encourage students to increase their likelihood of reporting and adopt the bystander response of reporting against BBB at school to ensure school health and safety.