Osteoarthritis (OA) patients have decreased functional ability and restricted access to healthcare facilities and are on a spectrum of medications. These can impact their oral health. This study aims to investigate the association between periodontal disease and OA disease parameters, specifically the functional disability and the medications taken. This was a cross-sectional study on OA participants recruited from the Hospital Canselor Tuanku Mukhriz. Periodontal health parameters were obtained from an oral examination of the participants. A Health Assessment Questionnaire (HAQ) was administered to ascertain the functional status of the participants. Out of the 130 participants recruited, 71 (54.6%) had periodontitis. There was a correlation between the teeth count with OA severity, where participants with a greater Kellgren–Lawrence score had less teeth (rs = 0.204, p = 0.025). Participants with a greater degree of functional limitation also had less teeth (rs = −0.181, p = 0.039) and a higher clinical attachment loss (rs = 0.239, p = 0.006). There were no associations found between the symptomatic slow-acting drugs in OA and periodontal health parameters. In conclusion, there was a high proportion of periodontitis in patients with OA. Functional disability was associated with measures of periodontal health. It is suggested that clinicians treating OA patients consider the need for a referral for dental care when managing this group of patients.