Pain assessment in cats is challenging, especially for non-veterinarians. Most validated acute pain scales are designed for clinical use, limiting their applicability for pet owners. This study developed a feline acute pain assessment scale for owners and evaluated its criterion validity, internal consistency reliability, and agreement with three veterinary scales: Glasgow Composite Measure Pain Scale-Feline (CMPS-Feline), Feline Grimace Scale (FGS), and Colorado State University Feline Acute Pain Scale (CSU-FPS). Of 146 enrolled cats, 130 were analyzed after exclusions. The owner-assessed scale showed strong correlation with CMPS-Feline (rho = 0.66) and moderate correlations with FGS (rho = 0.53) and CSU-FPS (rho = 0.57) (all p < 0.001). Agreement was substantial with CMPS-Feline (kappa = 0.74), moderate with FGS (kappa = 0.44), and fair with CSU-FPS (kappa = 0.28) (all p < 0.001). Internal consistency was acceptable (Cronbach’s alpha = 0.76). Receiver operating characteristic analysis demonstrated good discriminatory ability for identifying cats requiring analgesia, with area under the curve values of 0.87 (CMPS-Feline), 0.79 (FGS), and 0.75 (CSU-FPS). A cut-off score of 9 achieved 96% sensitivity and 78% specificity relative to CMPS-Feline. These results support the scale’s potential as a valid tool for pain detection by cat owners in non-clinical settings.