The Patient Knowledge of, and Attitude and Behaviour towards Pressure Ulcer Prevention Instrument (KPUP) was developed and validated using a two‐stage prospective psychometric instrument validation study design. In Stage 1, the instrument was designed, and it is psychometrically evaluated in Stage 2. To establish content validity, two expert panels independently reviewed each item for appropriateness and relevance. Psychometric evaluation included construct validity and stability testing of the instrument. The questionnaire was administered to a convenience sample of 200 people aged more than 65 years, living independently in the community; reliability and stability were assessed by test/retest procedures, with a 1‐week interval. Mean knowledge scores at ‘test’ were 11.54/20 (95% CI = 11.10‐11.99, SD: 3.07), and ‘retest’ was 12.24 (95% CI = 11.81‐12.66, SD: 2.93). For knowledge, correlation between the test/retest score was positive (r=. 60), attitude section‐inter‐item correlations ranged from r = −.31 to r = .57 (mean intraclass correlation coefficient of r = .42), and internal consistency for the retest was the same as the test (α = .41 for the eight items). For health behaviours, individual inter‐item correlations for test items ranged from r = −.21 to r = .41 for the 13 standardised items. Psychometric testing of the KPUP in a sample of older persons in the community provided moderate internal consistency and general high test‐retest stability.