Poor sleep quality is prevalent among older adults and is compounded by frailty and polypharmacy. This descriptive, cross-sectional study examines the associations between sleep quality, inappropriate medication use and frailty. The study was conducted among 151 residents of 11 aged care homes in three states in Malaysia; convenience sampling was used. Subjective sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), and Groningen Frailty Indicator (GFI) was used to assess frailty. Medication appropriateness was assessed using Drug burden Index (DBI), Potentially Inappropriate Medications (PIMs) and Potentially Inappropriate Prescriptions (PIPs). Most of the subjects (approximately 95%) reported poor sleep quality, as measured by a cut-off of global PSQI score of ≥ 5. With a second cut-off at 10, just over half (56%) reported moderately poor sleep quality followed by 39% who had very poor sleep quality. Most (90%) denied taking medication to improve their sleep during the previous month. There was no statistically significant association between medication inappropriateness (PIMs, PIPs, DBI) and global PSQI score. However, the average number of PIM was associated significantly with sleep efficiency (a measure of the actual ‘sleep to total time spent in bed) (p = 0.037). The average number of PIP was associated with subjective sleep quality (p = 0.045) and the use of sleep medications (p = 0.001), and inversely associated with sleep disturbance (0.049). Furthermore, frailty correlated significantly with poor overall sleep quality (p = 0.032). Findings support the need for medication review to identify and reduce PIMs and optimise prescriptions to improve sleep quality and hence, related health outcomes among residents of aged care homes.