The validity and reliability of the Persian version of the Modified Telephone Interview for Cognitive Status (P-TICS-M) in older adults living in the Iranian community for a comprehensive screening of mild cognitive impairment and dementia was investigated. In the first phase, translation, re-translation, and word-taking were performed by using the face validity and content validity. In the second phase, a stratified convenient sampling with 150 participants aged ≥60 years was conducted based on cognitive status using the global deterioration scale in 2018. The external and internal reliability of the P-TICS-M using the interclass correlation coefficient and Cronbach's alpha coefficient of total items of this tool were estimated. The mean age of the participants was 68.6 (standard deviation±7.4) years. According to global deterioration scale, 87 (58.0%) had normal cognition, 40 (26.7%) had mild cognitive impairment, and 23 (15.3%) had dementia. The Spearman's correlation coefficient between P-TICS-M scores and Mini-Mental State Examination scale was 0.764. In exploratory factor analysis, seven domains were detected, which were compatible with those defined by the tool developer. The Cronbach's alpha of the P-TICS-M was 0.920. The absolute agreement between test-retest score was >0.90. The sensitivity of 92.2, 94.8, and 100%, and also the specificity of 79.4, 88.2, and 89.8% were calculated for detecting subjects with dementia, respectively. Furthermore, a mild cognitive impairment cutoff of >28 was determined. The development and validation of a P-TICS-M tool can be useful in identifying older adult people with cognitive impairment. Demographic characteristics (level of education, age) can also affect the cutoff point of this tool.