Background: The assessment of emotional well-being (EWB) has become increasingly recognized for understanding overall health. An EWB assessment that considers individuals' cultural backgrounds and experiences, particularly those of immigrants, is essential to respecting their unique values within their health care experiences. However, using the same universal assessment measure across cultures may fail to account for cultural diversity, thus hindering the delivery of person-centred care. Therefore, there is a need to examine how EWB measures function among culturally diverse immigrant populations.      Purpose: This study aimed to enhance person-centred care by examining measurement bias related to differences in how East Asian immigrants responded to self-reported items for measuring EWB compared to non-immigrant White people in Canada. Methods: The data were drawn from the Equitable People-Centred Health Measurement survey. EWB was measured using the “Feelings” item bank of the CAT-5D-QOL, which consists of 43 items about depressive symptoms, anxiety, and positive feelings.  Propensity score matching was used to create a balanced sample of East Asian immigrants and White non-immigrants.  Measurement bias was examined with Multiple Indicator Multiple Causes Item Response Theory model to test for differential item functioning (DIF) between the two groups. Results: The sample included 580 White respondents (48.6% male, 51.4% female, mean age=45.3 years) and 580 East Asian immigrants (49.8% male, 50.2% female, mean age=48.6 years). The analysis revealed statistically significant DIF for 21 of the 43 items, indicating that these items do not measure EWB in the same way for East Asian immigrants. The item, “During the past 7 days, how much of the time did you feel that you have a number of good qualities?” showed the significant DIF. Conclusion: This result demonstrates the importance of considering cultural background when using EWB items to ensure culturally sensitive and equitable health that reflects the values of person-centred care for East Asian immigrants.