Recent years have seen an increase in regional ozone (O3) pollution in China. This study explored the interannual variability in daily maximum 8-h average O3 concentration (MDA8-O3) in Northeast China (NEC) and its three subregions (Liaoning, Jilin, and Heilongjiang) during 2013–2021, and identified the key meteorological drivers underlying the observed variability. The Kolmogorov–Zurbenko filtering technique was applied to a stepwise multiple linear regression model to decompose the meteorological and anthropogenic contributions to annual MDA8-O3 trends. The results showed that the spatiotemporal variation of MDA8-O3 in NEC is characterized by a high–south and low–north pattern with an MDA8-O3 hotspot in the Bohai Rim area. Over the 9-year study period, a significant increasing trend (∼2.5% a−1, P < 0.05) in the regional mean of the annual 90th percentile of MDA8-O3 was detected across NEC. This trend was strongly relevant to changes in relative humidity and surface solar radiation downward (SSRD). Statistical analyses revealed that SSRD dominated MDA8-O3 variability spatially over almost the entire NEC region. Additionally, the contribution decomposition suggested that the trend of increase in annual average MDA8-O3 in NEC was dominated by anthropogenic emission change, which explained 91.9% of the total variation. Regionally, although the dominant role of emissions has not changed, the meteorology-driven anomalies also explained −4.3%–3.3% of the annual average MDA8-O3 variation. This study provides insight into decoupling the complex relationships between long-term variability in regional O3 pollution and both anthropogenic emissions and meteorology, which could provide valuable information for future efforts to address the O3 pollution in NEC.