Problematic social media use is a maladaptive and detrimental pattern of addictive behaviours towards social media. Although problematic social media use has been based upon framework characterizing behavioural addiction, it is currently not part of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Morphological abnormalities of the striatum have been found in behavioural addictions, however the neurobiological basis of problematic social media use has yet to be investigated. The present study aimed to investigate striatal volume and shape in association with problematic social media use and frequency of social media use. Higher levels of problematic social media use and increased frequency of use were not significantly related to the volume of the striatum. However, when examining the shape of the striatum, surface area deformations were significantly associated with higher problematic social media use. We call for continued research to further validate problematic social media use as a behavioural addiction.