Mounting evidence suggests that obsessive intrusions are often accompanied and amplified by perceptual experiences of different modalities (e.g., feeling dirt on one's skin while experiencing intrusive thoughts about contamination). Pilot studies conducted online with individuals endorsing mild obsessive–compulsive symptoms have linked the co‐occurrence of perceptual experiences and obsessions to the severity of subsequent compulsive behaviour as well as low insight. However, it is presently unclear whether sensory experiences accompany all types of obsessional thoughts or are restricted to certain preoccupations (e.g., contamination and aggression). The present study examined a clinical inpatient and outpatient sample with a formally diagnosed obsessive–compulsive disorder (N = 34). Perceptual properties of intrusive thoughts were assessed with the Sensory Properties of Obsessions Questionnaire. The prevalence of perception‐laden obsessive thoughts was comparable with prior studies (73.5%), but the intensity was significantly greater. No association was observed between perceptual experiences and expert‐rated insight. However, the severity of perception‐laden obsessions predicted the frequency of and impairment associated with compulsive behaviour. This was particularly strong for obsessions about contamination. The present study confirms the high prevalence and clinical relevance of perceptual experiences that accompany obsessions and further challenges the traditional trichotomy splitting mental phenomena into thoughts, intrusions, and hallucinations.