AimTo assess the psychometric properties of the Thai version of Caregiver Contribution to Self‐Care of Chronic Illness Inventory version 2 (CC‐SC‐CII‐v2) among primary caregivers of individuals with any single or multiple chronic illnesses.BackgroundThe instrument encompasses three scales that evaluate Caregiver Contribution to Self‐Care (CC‐SC) Maintenance, Monitoring and Management.MethodsThe English version CC‐SC‐CII‐v2 was translated and adapted for Thai context, and a cross‐sectional multicenter study involved 430 caregivers from 16 primary care centres in Thailand. Structural validity, internal consistency reliability and test–retest reliability were examined.ResultsThe original two‐factor CC‐SC Maintenance scale required a re‐specified model for good fit, while the CC‐SC Monitoring and CC‐SC Management scales fit well. The simultaneous model of three scales demonstrated satisfactory fit. The CC‐SC Maintenance and CC‐SC Management scales both had a composite reliability index of 0.85, with omega coefficients of 0.86 and 0.83, respectively. CC‐SC Monitoring had an alpha coefficient of 0.89. The intraclass correlation coefficients ranging from 0.84 to 0.91, indicating good test–retest reliability.ConclusionThe Thai CC‐SC‐CII‐v2 is a valid and reliable instrument that can provide clinicians and investigators with an evaluation of the contributions of caregivers to the self‐care of patients with chronic illnesses.