Background: Ethnic and socioeconomic disparities in cancer outcomes are exacerbated by clinical trial underrepresentation. This study aims to identify inequalities in ethnicity and socioeconomic features among ovarian cancer clinical trial participants in two London cancer centres. Methods: All ovarian cancer patients treated between 2017 and 2022 were included. Patients participating in clinical trials were classified as the trial population (TP); the remainder were considered the non-trial population (NTP). Data on disease characteristics and sociodemographic features, including ethnicity and Indices of Multiple Deprivation (IMD) deciles, were accessed from electronic patient records. Results: Of the 892 patients, 212 (24%) were enrolled in trials: 87 in Phase II, 103 in Phase III, and 21 in prospective, non-investigational medicinal product trials. The TP were more likely to be of White ethnicity (72.6% vs. 57.5%; p < 0.001), younger (mean age 58 vs. 60; p = 0.003), living in less deprived areas (most deprived tercile: 21.2% vs. 34.0%; p = 0.004), and English-speaking (95.8% vs. 90.9%; p = 0.041). In the multivariate analysis, White ethnicity (p < 0.0001), age (p = 0.003), IMD decile (p = 0.007), and interpreter requirement (p = 0.037) were independent predictors of trial participation. Conclusions: Ethnic and socioeconomic inequalities affect trial participation, potentially worsening health disparities in ovarian cancer patients. Strategies to overcome trial recruitment barriers for underserved groups are needed to improve the equity of care.