BACKGROUND: The population of older adults (ie, those aged ≥55 years) in England is becoming increasingly ethnically diverse. Previous reports indicate that ethnic inequalities in health exist among older adults, but information is limited by the paucity of data from small minority ethnic groups. This study aimed to analyse inequalities in health-related quality of life (HRQoL) and five determinants of health in older adults across all ethnic groups in England. METHODS: In this cross-sectional study, we analysed data from five waves (July 1, 2014, to April 7, 2017) of the nationally representative English General Practice Patient Survey (GPPS). Study participants were adults aged 55 years or older who were registered with general practices in England. We used regression models (age-adjusted and stratified by gender) to estimate the association between ethnicity and HRQoL, measured by use of the EQ-5D-5L index and its domains (mobility, self-care, usual activities, pain or discomfort, and anxiety or depression). We also estimated associations between ethnicity and five determinants of health (presence of long-term conditions or multimorbidity, experience of primary care, degree of support from local services, patient self-confidence in managing own health, and degree of area-level social deprivation). We examined robustness to differential handling of missing data, alternative EQ-5D-5L value sets, and differences in area-level social deprivation. FINDINGS: There were 1 416 793 GPPS respondents aged 55 years and older. 1 394 361 (98·4 per cent) respondents had complete data on ethnicity and gender and were included in our analysis. Of these, 152 710 (11 per cent) self-identified as belonging to minority ethnic groups. HRQoL was worse for men or women, or both, in 15 (88·2 per cent) of 17 minority ethnic groups than the White British ethnic group. In both men and women, inequalities were widest for Gypsy or Irish Traveller (linear regression coefficient −0·192 [95 per cent CI −0·318 to −0·066] in men; −0·264 [–0·354 to −0·173] in women), Bangladeshi (−0·111 [–0·136 to −0·087] in men; −0·209 [–0·235 to −0·184] in women), Pakistani (−0·084 [–0·096 to −0·073] in men; −0·206 [–0·219 to −0·193] in women), and Arab (−0·061 [–0·086 to −0·035] in men; −0·145 [–0·180 to −0·110] in women) ethnic groups, with magnitudes generally greater for women than men. Differentials tended to be widest for the self-care EQ-5D-5L domain. Ethnic inequalities in HRQoL were accompanied by increased prevalence of long-term conditions or multimorbidity, poor experiences of primary care, insufficient support from local services, low patient self-confidence in managing their own health, and high area-level social deprivation, compared with the White British group. INTERPRETATION: We found evidence of wide ethnic inequalities in HRQoL and five determinants of health for older adults in England. Outcomes varied between minority ethnic groups, highlighting heterogeneity in the direction and magnitude of associations. We recommend further research to understand the drivers of inequalities, together with policy changes to improve equity of socioeconomic opportunity and access to services for older adults from minority ethnic groups. FUNDING: University of Manchester and National Institute for Health Research. [Abstract]