Low back pain is prevalent in equestrian athletes, but prevalence and associated factors are unknown in the Portuguese equestrian population. A questionnaire regarding low back pain and possible associated factors was answered by 347 respondents. Estimated 12-month prevalence was 67.1%. The probability of suffering from low back pain was higher in individuals with higher weekly riding workload, that reported equestrianism as their main occupation and that performed daily stable duties. The Roland Morris disability questionnaire was applied to the respondents that stated having experienced low back pain in the past 12 months, resulting in an average score of 5.39 ± 4.42. 63.1% of respondents stated that low back pain impaired their performance. Individuals that stated equestrianism was their main occupation showed a significant higher risk (OR = 1.759) of exhibiting a score ≥ 4, as measure of dysfunctionality. Age and high body mass index were also associated to a dysfunctional score. Further research is needed to fully understand the impacts of low back pain in Portuguese equestrian athletes.