Background: To determine if the COVID-19 pandemic influenced students' cardiorespiratory fitness (CRF), this study examined the prevalence of meeting a health-related standard for CRF in public school students before, during and after the pandemic. Methods: A repeated cross-sectional study design was used, and multilevel logistic regression was employed to compare the prevalence of students meeting the CRF standard during the four school years preceding the pandemic (2016-2017 to 2019-2020) with the 2 years during the pandemic (2020-2021 to 2021-2022) and with 2 years after the pandemic (2022-2023 to 2023-2024). Students' CRF data were provided by 21 school districts that, between 2016-2017 and 2023-2024, consistently participated in a statewide survey of health-related fitness. Results: Before the pandemic 52.4% of students met the standard for CRF. This prevalence was reduced to 44.3% during the pandemic (AOR = 0.69, 95% CI = 0.67, 0.70) and remained reduced at 47.1% after the pandemic (AOR = 0.77, 95% CI = 0.76, 0.79). Implications for School Health: During periods of societal disruption, such as a pandemic, school personnel should adopt practices aimed at supporting students' CRF. Conclusions: The COVID-19 pandemic was associated with reduced CRF in public school students, and this trend persisted for at least two school years following the pandemic.