| Summary: | (1) Background: As the most common eye disease diagnosed in emergency departments, conjunctivitis has caused serious health and economic burdens worldwide. However, whether air pollution may be a risk factor for conjunctivitis is still inconsistent among current evidence. (2) Methods: We searched the literature on the relationship between air pollution and conjunctivitis in multiple English databases before 18 March 2019. Meta-analysis, meta-regression, and funnel plots were used to integrate the data, identify the sources of bias, and determine the publication bias, respectively. (3) Results: A total of 2450 papers were found, 12 of which were finally included. The pooled relative risk for each 10 μg/m<sup>3</sup> increase of air pollution on conjunctivitis was 1.0006 (95%CI: 0.9993−1.0019) for CO, 1.0287 (1.0120−1.0457) for NO<sub>2</sub>, 1.0089 (1.0030−1.0149) for O<sub>3</sub>, 1.0004 (0.9976−1.0032) for PM<sub>2.5</sub>, 1.0033 (0.9982−1.0083) for PM<sub>10</sub>, and 1.0045 (0.9908−1.0185) for SO<sub>2</sub>. In the subgroup, PM<sub>2.5</sub> and O<sub>3</sub> had a greater impact on conjunctivitis risk in women than in men, and people <18 years old than those ≥18 years old. Relative humidity significantly modified the risk of O<sub>3</sub> on conjunctivitis (<i>p</i> = 0.023), explaining 45% of the between-study heterogeneity. (4) Conclusion: Globally, air pollution has considerable health risks for conjunctivitis. Females and the youth were more vulnerable to PM<sub>2.5</sub>, NO<sub>2</sub>, and O<sub>3</sub>. Reductions of air pollution levels are still warranted to protect the vulnerable populations.
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