Equestrian equipment is often used to maintain control of horses while riding, training or handling them and therefore to optimize human and horse safety. However, equipment that has been incorrectly selected or inappropriately used may result in horses exhibiting conflict-related behavior. Characterizing associations between apparatus use and unwelcome horse behavior could benefit both horse welfare and human safety by elucidating the ontogeny of undesirable equine responses and promoting the ethical use of equipment. The current study explored associations between commonly used apparatus and the reported behaviors of the ridden horse, using an online survey that attracted 1,101 Australian respondents. Chi-square tests of association revealed thirteen (9.1%) significant relationships between any unwanted behavior and single items of apparatus used during riding. Analysis of combinations of apparatus that impose aversive stimuli (e.g., harsh bits for deceleration, and spurs for acceleration) revealed that 37.19% of combinations of such items were significantly related to unwanted/conflict equine behaviors. Additional analysis demonstrated no significant difference in the unwanted behavior of horses ridden in bitless versus bitted bridles. This study has demonstrated associations between unwanted ridden behaviors and type of apparatus used, particularly when multiple items are used to apply opposing aversive stimuli. Whilst these results do not imply causation, they may be used to better inform equestrians’ choice and ethical use of apparatus.