This study investigates how perceived unfair treatment, towards self and observed towards others due to ethnicity, is associated with periodontitis among diverse Hispanic/Latino adults, accounting for sociodemographic, health behavior, and acculturation factors. Baseline (2008-2011) dental and survey data from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), a multicenter epidemiologic study, were analyzed (N = 12,750). Crude and adjusted prevalence ratios and confidence limits were estimated. Half (49%) reported never being treated unfairly, while 41% reported they were sometimes, and 10% reported it often/always. One third (32%) never saw others treated unfairly, while 42% reported it sometimes, and 26% reported it often/always. In the final fully adjusted model, the prevalence of periodontitis was higher among adults who were as follows: non-Dominican, older, male, had a past year dental visit, current and former smokers, and among those who observed unfair treatment towards others. Lower prevalence was associated with higher income, higher educational attainment, less than full-time employment, reporting experiencing unfair treatment, higher acculturation scores, and having health insurance. Perceived unfair treatment towards self was negatively associated with periodontitis prevalence, while observed unfair treatment towards others was positively associated with the outcome among diverse Hispanics/Latinos. The associations between unfair treatment and periodontitis warrant further exploration.