It is important to understand barriers to Physical Activity (PA), particularly for under researched populations. While a lack of PA has been acknowledged as an important issue for those living in Afghanistan, there have been no published studies exploring barriers to PA within this population. Therefore, the purpose of this study was to explore barriers to PA for Afghans and how these differ depending on where they reside: UK or Afghanistan. 930 participants, 578 (291 males; 287 females) were recruited from Afghanistan and 352 (267 males; 85 females) from the UK. A culturally nuanced questionnaire exploring barriers to PA was developed and used to collect data via an online survey software programme. Bayesian ordinal models explored differences between population groups, with results suggesting some barriers are shared across populations but others more pertinent for a particular group. Lack of time and being too tired were barriers for both populations, but were rated higher by those living in Afghanistan; as was a lack of confidence and being uncomfortable with exercise clothing. Afghan females perceived a lack of single-sex facilities, not being able to participate in PA with males, and having to be fully covered outside of the home as important barriers to their PA, but these were more of a barrier for those residing in the UK. The findings highlight important considerations for trying to engage these populations in PA.