Injuries among ultramarathoners are influenced by training load, recovery characteristics, anthropometric, and biomechanical characteristics. Beyond these contributors, there is increasing interest in understanding how psychological and behavioural factors may influence injury frequency and severity. Our purpose was to identify the prevalence of injuries among Brazilian ultramarathoners and the individual, training, and psychological variables associated with a higher risk of injuries. This is a cross-sectional, web-based research design that sampled Brazilian ultramarathoners of both sexes. Data was collected through an online survey during April and June 2025. The questionnaire collected information about: sex, age, body weight and height, training parameters, injury occurrence, general anxiety disorder (GAD), and exercise addiction. Ultramarathoners were classified for the GAD and exercise addiction, using specific cut-off points. An independent t-test and logistic regression model were used for the total sample and both sexes, adopting 95% of confidence interval (CI). The study included 495 ultramarathoners (44.5 ± 9.9 years). Injury prevalence was 27.7%. For the total sample, BMI (OR = 1.08; 95%CI = 1.00 to 1.13), GAD low (OR = 1.62; 95%CI = 1.00 to 2.64), and GAD severe (OR = 3.26; 95%CI = 1.32 to 8.03) increased the injury risk. For women, age and GAD severe (OR = 15.92; 95%CI = 2.47 to 102.31) were significantly associated with injury, while for men, an association was observed for GAD low (OR = 1.76; 95%CI = 1.03 to 3.02). Age, BMI, and generalized anxiety disorder were significantly associated with injury risk, with women classified as having severe symptoms showing greater vulnerability.