Head injuries account for 15% of snowsport-related injuries and are the leading cause of fatalities in snowsports. Research indicates snowsport helmets could reduce head injuries by between 21% and 45%, although optimising performance through realistic testing could further reduce injuries. Notably, 65–70% of snowsport traumatic brain injuries occur against ice or snow, a low-friction surface. Therefore, this study aimed to evaluate how surface friction affects snowsport helmets’ oblique impact response kinematics. We measured helmet static coefficient of friction (COF) against high-COF (80-grit sandpaper) and low-COF (steel) surfaces using a tribometer. Oblique impact testing of 10 snowsport helmet models was done at 5 m/s onto a 45-degree anvil with high-COF and low-COF surfaces. Linear mixed-effect models were used to compare the effects of location and friction surface on linear and rotational kinematics. The average COF of helmet shells against 80-grit sandpaper was 0.76 ± 0.03 and 0.27 ± 0.09 against steel. Surface friction affected linear and rotational head impact kinematics and changed how the helmets rotated off the anvil. These effects underscore the need for sport-specific lab testing. Such research is crucial for improving helmet design to minimise injury risks and optimise protection for snowsport athletes.