The coronavirus disease 2019 (COVID-19) pandemic has led to economic contraction and significant restrictions on society. The shock to the economy could lead to a deterioration of physical health outcomes, including dental health. The present study investigated the association between worsened socioeconomic conditions due to the COVID-19 pandemic and dental pain in Japan. The mediating effects of psychological distress and oral health–related behaviors were also evaluated. Cross-sectional data from the Japan COVID-19 and Society Internet Survey conducted from August to September 2020 (n = 25,482; age range, 15–79 y) were analyzed. Multivariable logistic regression models were fitted to evaluate the independent associations of household income reduction, work reduction, and job loss due to the COVID-19 pandemic with dental pain within a month. Dental pain was reported by 9.8%. Household income reduction, work reduction, and job loss were independently associated with dental pain after adjusting for confounders (odds ratios: 1.42 95% confidence interval (CI), 1.28−1.57, 1.58 95% CI, 1.41−1.76, 2.17 95% CI, 1.64−2.88, respectively). The association related to household income reduction was mediated by psychological distress, postponing dental visits, toothbrushing behavior, and between-meals eating behavior by 21.3% (95% CI, 14.0−31.6), 12.4% (95% CI, 7.2−19.6), 1.5% (95% CI, −0.01 to 4.5), and 9.3% (95% CI, 5.4−15.2), respectively. Our findings showed that worsened socioeconomic conditions due to the COVID-19 pandemic deteriorated dental health. Policies that protect income and job loss may reduce dental health problems after the pandemic.