With pervasive health misinformation and mistrust, many of those at greatest risk from COVID-19 have demonstrated lower vaccine acceptance. In Chicago, IL, surveillance data has revealed lower rates of vaccine uptake among Black and Latinx individuals compared with others. We partnered with two local federally qualified health centers (FQHCs) to develop and implement language-concordant, low literacy patient education materials to promote COVID-19 vaccine knowledge, acceptance, and uptake. Our multi-phase study included: 1) iterative content generation and refinement by health literacy experts, health center providers and staff, and community-dwelling adults; and 2) materials testing via a two-arm randomized experiment among adults from Latinx communities in the Chicagoland area. Results indicate that our English and Spanish-language COVID-19 Fact Sheets increase knowledge about COVID-19 vaccination. These materials are publicly available and can be used by health centers or community organizations to promote COVID-19 vaccination among diverse populations.