In obsessive-compulsive disorder (OCD), excessive reassurance seeking (RS) has been construed as overt direct questions and/or covert subtle statements which prompt information to allay obsessional doubts and/or fears. However, an exclusively verbal conceptualization of RS lacks theoretical justification and fails to explain the use of nonverbal actions (e.g., prolonged pauses) ostensibly to prompt reassurance following an experimental manipulation of responsibility (Leonhart & Radomsky, 2019b). Nonverbal RS (NVRS) may reinforce symptoms ‘under the radar’ of those with OCD, loved ones, and/or helping professionals. The lack of research into NVRS may limit the effectiveness of cognitive-behavioural therapy (CBT)–the treatment of choice for OCD. The present mixed-methods doctoral research was conducted to examine the manifestations and functions of NVRS in OCD. A checklist of NVRS behaviours was developed from observations and a review of the literature on RS and nonverbal communication. In Study 1, experimentally increased high ([HR] vs. decreased, low responsibility [LR]) resulted in more verbal RS (VRS) as reported by participants (N = 86) and a trained actor from whom reassurance was sought, and critically, in more NVRS according to the actor. As predicted, responsibility beliefs may have similar impacts on checking, VRS, and NVRS. Further, a significant condition × time × person interaction was observed, such that HR participants reported a smaller transfer of responsibility to the actor while LR participants reported a comparatively larger transfer to themselves following the RS opportunity. Study 2 was designed to learn if people with lived experience of seeking and providing reassurance endorsed similar and/or additional NVRS behaviour. Twelve pairs of people who met criteria for OCD and partners of their choosing (N = 24) were interviewed. Participants with OCD utilized several NVRS behaviours when given an opportunity to seek reassurance from their partners. Prominent behaviours were those which reportedly occurred during most interactions and were used at least daily to seek reassurance according to participant-partner pairs: close examination of others’ reactions, direct eye contact, pauses to allow for reassurance, and forehead wrinkling. NVRS, like VRS, may result in neutralized obsessions, but it may also have unique functions (e.g., avoided social consequences, better effectiveness). Unexpectedly, there was no clear evidence that people with OCD were unaware of their NVRS. Implications for cognitive-behavioural theories of and therapies for RS generally and NVRS specifically are discussed.