This study aimed to better understand the factors influencing the provision of sexuality-related post-stroke rehabilitation services by clinicians on different sites and to explore strategies to improve post-stroke rehabilitation services with stakeholders. A qualitative study with co-design methods was conducted with 20 clinicians from five post-stroke rehabilitation centers in Canada, 1 manager and 1 patient-partner. Participants either took part in a focus group or in sessions of an adapted version of the LEGO Serious Play method to explore influencing factors and strategies of improvement in relation to post-stroke sexual rehabilitation services. Thematic analysis was conducted semi-deductively using the Theoretical Domains Framework (TDF), the Capability, Opportunity, Motivation and Behaviour (COM-B) system and the Behaviour Change Wheel (BCW). A total of twenty factors pertaining either to the categories of Capability (n = 8; e.g., Sexual rehabilitation procedural knowledge), Motivation (n = 4; e.g., Professional boundaries) or Opportunity (n = 8; e.g., Workload) were perceived as influencing provision of sexual rehabilitation services by participants. A theoretical model was conceptualized. Strategies (n = 10) were categorized in concordance with the BCW as Training (n = 1), Enablement (n = 5) or Environmental restructuring (n = 4). This study showed that factors influencing provision of post-stroke rehabilitation services were numerous and interrelated, and that various strategies aiming either clinicians or the rehabilitation environment would be relevant to improve services. This study will help guide the design and implementation of future interventions studies aiming at improving post-stroke sexual rehabilitation services.