We investigated the prevalence of body image dissatisfaction (BID) and associated factors among professors and undergraduate students in Brazil during the COVID-19 pandemic. Using Stunkard’s Figure Rating Scale, BID was analyzed in a sample of 2,220 adults. The independent variables were sociodemographic, lifestyle, mental health symptoms, COVID-19-related factors, disordered eating, experience of weight stigma, and weight change concerns. We used a multinomial logistic regression analysis. The overall prevalence of BID was 82.5% (69.0% due to excess weight), with more professors dissatisfied by excess weight than undergraduate students (78.9% vs. 61.2%, p < 0.001). In the adjusted model, being a young adult (PR, 1.201, 95% CI: 1.128; 1.279), married or in a stable union (PR, 1.088, 95% CI: 1.027; 1.152), reporting of binge eating episode (PR, 1.120, 95% CI: 1.068; 1.173), concern about weight gain (PR, 1.394, 95% CI: 1.310; 1,483), and experience of excess weight stigma (PR, 1.193, 95% CI: 1.141; 1.248) increased the prevalence of BID due to excess weight. While males (PR, 1.578, 95% CI: 1.328; 1.875), moderate to severe depressive symptoms (PR, 1.217, 95% CI: 1.011; 1.465), the concern of losing weight (PR, 1.494, 95% CI: 1.221; 1.830), and experience of low weight stigma (PR, 2.620, 95% CI: 2.093; 3.280) increased the prevalence of BID due to low weight. Different factors associated with BID were observed between students and professors. Bearing in mind the complexity of body image, it is essential to consider different public health interventions and the COVID-19 pandemic’s influence on reducing BID among Brazilian adults, especially susceptible groups.