Knee osteoarthritis (KOA) is a chronic disease accompanied by debilitating symptoms including pain, stiffness, and limited physical functionality, which have been shown to be associated with pain catastrophizing. Previous studies have revealed racial discrepancies in pain catastrophizing, notably between Hispanics and non-Hispanics while pointing to potential health disparities. Using a conceptual model, this study aimed to investigate racial differences in associations between KOA symptoms with specific pain catastrophizing domains (rumination, magnification, and helplessness). Patients with KOA (n = 253; 147 Hispanics, 106 non-Hispanic Whites) completed a survey that included measures of knee symptoms, pain catastrophizing, and demographic variables. Structural equation modeling revealed that among Hispanics, each pain catastrophizing domain (rumination, magnification, and helplessness) was associated with at least two symptomatic experiences, including pain severity and difficulty in physical function. Specifically, pain severity was associated with (a) rumination: β = 0.48, p < 0.001, (b) magnification: β = 0.31, p = 0.003; and (c) helplessness: β = 0.39, p < 0.001). Additionally, a lower score in physical function was associated with higher magnification (β = 0.26, p = 0.01), and helplessness (β = 0.25, p = 0.01). Among non-Hispanic White patients, pain severity was further associated with two domains of pain catastrophizing, including rumination (β = 0.39, p < 0.001) and helplessness (β = 0.35, p = 0.01). In addition, association pathways for demographic variables revealed that older Hispanics experienced greater challenges with higher pain severity (β = 0.26, p = 0.01) and greater difficulty with physical function (β = 0.31, p < 0.001) while Hispanics females experienced higher pain (β = 0.19, p = 0.03). These findings highlight the importance of designing tailored interventions that consider key demographic factors such as age, and gender, to improve physical function that might alleviate pain catastrophizing among Hispanics with KOA.