The purpose of this study was to assess differences in COVID-19 vaccine willingness and uptake between low-income and non-low-income adults and across race-ethnicity. We utilized data from the COVID-19's Unequal Racial Burden online survey, which included baseline (12/17/2020-2/11/2021) and 6-month follow-up (8/13/2021-9/9/2021) surveys. The sample included 1,500 Black/African American, Latino, and White low-income adults living in the U.S. (N = 500 each). A non-low-income cohort was created for comparison (n = 1,188). Multinomial logistic regression was used to assess differences in vaccine willingness and uptake between low-income and non-low-income adults, as well as across race-ethnicity (low-income adults only). Only low-income White adults were less likely to be vaccinated compared to their non-low-income counterparts (extremely willing vs. not at all: OR = 0.58, 95% CI = 0.39-0.86); low-income Black/African American and Latino adults were just as willing or more willing to vaccinate. At follow-up, only 30.2% of low-income adults who reported being unwilling at baseline were vaccinated at follow-up. White low-income adults (63.6%) appeared less likely to be vaccinated, compared to non-low-income White adults (80.9%), low-income Black/African American (70.7%), and low-income Latino adults (72.4%). Distrust in the government (46.6), drug companies (44.5%), and vaccine contents (52.1%) were common among those unwilling to vaccinate. This prospective study among a diverse sample of low-income adults found that low-income White adults were less willing and less likely to vaccinate than their non-low-income counterparts, but this difference was not observed for Black/African American or Latino adults. Distrust and misinformation were prevalent among those who remained unvaccinated at follow-up.