Uric acid (UA) is a major antioxidant molecule in the human blood, and it has been linked with cell longevity. However, it is unclear whether serum UA levels are associated with red blood cell (RBC) indexes. This cross-sectional study included 10,759 Chinese subjects, recruited from the Shanghai Xuhui Central Hospital from January 2014 to December 2017. The participants were categorized into gender groups and then further divided into three different subgroups according to their UA reference range as follows: low (male (UA < 0.202 mmol/l), female (UA < 0.143 mmol/l)), normal (male (0.417 mmol/l > UA ≥ 0.202 mmol/l), female (0.339 mmol/l > UA ≥ 0.143 mmol/l)), and high (male (UA ≥ 0.417 mmol/l), female (UA ≥ 0.339 mmol/l)). The associations of UA levels with RBC parameters were analyzed using 1-way ANOVA, Pearson correlations, and multivariate linear regression. The levels of mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, RBCs, and hemoglobin were lowest in the low UA group, followed by the normal UA group and high UA group (p < 0.001). Pearson analysis showed that there was a statistically significant correlation between UA levels with mean corpuscular hemoglobin, mean corpuscular hemoglobin concentrations, mean corpuscular volumes, RBC counts, and hemoglobin (p < 0.05). Multiple linear regression analysis suggested that there were statistically significant positive correlations between UA levels and RBC counts (B = 0.245, p < 0.001, 95% CI = 0.003 to 0.092), as well as UA levels and hemoglobin concentrations (B = 0.138, p < 0.001, 95% CI = 0.002 to 0.082). Furthermore, similar results were observed in both the male and female subgroups. The serum UA levels may be independently associated with RBC parameters, regardless of sex, and UA may protect RBCs owing to its antioxidant effect.