Aim. Utilizing a cross-sectional case control design, the aim of this study was to evaluate the functional fitness and self-reported quality of life differences in older people diagnosed with knee osteoarthrosis (O) who participated in health promotion groups. Methods. Ninety older women were distributed into two groups: control without O of the knee (C, n = 40) and a group diagnosed with primary and secondary knee O with grade II or higher, with definite osteophytes (OA, n = 50). Functional fitness was evaluated by specific tests, and the time spent in physical activity and quality of life was evaluated by the IPAQ and WHOQOL (distributed in four domains: physical: P, psychological: PS, social: S, and environmental: E) domain questionnaires. Results. No differences were found between ages of groups (C: 66 ± 7; OA: 67 ± 9; years). The values of the chair stand test (rep) in the OA (13 ± 5) group were different when compared to C group (22 ± 5). For the 6-minute walk test (meters), the values obtained for the C (635 ± 142) were higher (P < 0.01) than the OA (297 ± 143) group. The time spent in physical activity (min) was greater (P < 0.001) in the control (220 ± 12) group compared to OA (100 ± 10) group. Higher values (P < 0.001) in all domains were found in the C (P: 69 ± 16, PS: 72 ± 17, S: 67 ± 15, E: 70 ± 15) group compared to OA (P: 48 ± 7, PS: 43 ± 8, S: 53 ± 13, E: 47 ± 14) group. Conclusion. Our data suggests that knee O, in older women, can promote a decline in time spent performing physical activity and functional fitness with decline in quality of life with an increase in sitting time.