The role of healthcare provider ownership in shaping health system performance remains contested. An umbrella review was conducted to synthesise evidence on the relationship between healthcare provider ownership and performance in high-income countries. Systematic reviews were included that examined performance of healthcare providers based on ownership status. Searches yielded 1,862 results, with 31 systematic reviews meeting the inclusion criteria, and one further systematic review identified through grey literature searches. Following the exclusion of 10 reviews classified as low-quality and two previous umbrella reviews both published in 2014, 20 reviews were eligible for data extraction and synthesis. Inconsistent evidence was found across reviews between healthcare provider ownership and several performance indicators including health outcomes, technical efficiency, and patient satisfaction. Private hospitals tend to serve wealthier patients, select less complex or costly patients, and charge higher payments for care than public comparators. Private for-profit (FP) providers of hospital and long-term care generally had poorer workforce outcomes than private not-for-profit or public providers, including reduced staffing levels, higher workloads, and lower job satisfaction. Private PF hospitals and nursing homes had improved financial performance based on revenues or profit margins. Our findings underscore the need for nuanced regulatory responses to the expansion of private FP provision within publicly funded systems.