This systematic review and meta-analysis aimed to critically assess the correlation between periodontitis (PD) and dental caries. The study included 18 studies from PUBMED and EMBASE databases, covering the period from 1994 to 2023. The Newcastle–Ottawa scale was used to evaluate the risk of bias in the included studies. The results showed that PD was significantly associated with an increased risk of dental caries (OR = 1.57, 95% CI: 1.20–2.07). The severity of PD was also a significant factor, with moderate (OR = 1.38, 95% CI: 1.15–1.66) and severe (OR = 2.14, 95% CI: 1.74–2.64) PD being linked to higher caries risk. Patients with PD had a higher mean number of decayed, missing, and filled teeth (DMFT) and decayed and filled root teeth (DFR) compared to those without PD (WMD_DMF = 0.87, 95% CI: -0.03–1.76; WMD_DFR = 1.13, 95% CI: 0.48–1.78). Conversely, patients with caries had an elevated risk of PD (OR = 1.79, 95% CI: 1.36–2.35). However, Streptococcus mutans, a major caries pathogen, showed a negative correlation with several key pathogens of PD. The study concluded that there is a positive correlation between PD and dental caries at both clinical and bacterial levels. Further research is needed to understand the mechanisms underlying this association and to develop innovative prevention strategies for these two prevalent oral diseases.This systematic review and meta-analysis aimed to critically assess the correlation between periodontitis (PD) and dental caries. The study included 18 studies from PUBMED and EMBASE databases, covering the period from 1994 to 2023. The Newcastle–Ottawa scale was used to evaluate the risk of bias in the included studies. The results showed that PD was significantly associated with an increased risk of dental caries (OR = 1.57, 95% CI: 1.20–2.07). The severity of PD was also a significant factor, with moderate (OR = 1.38, 95% CI: 1.15–1.66) and severe (OR = 2.14, 95% CI: 1.74–2.64) PD being linked to higher caries risk. Patients with PD had a higher mean number of decayed, missing, and filled teeth (DMFT) and decayed and filled root teeth (DFR) compared to those without PD (WMD_DMF = 0.87, 95% CI: -0.03–1.76; WMD_DFR = 1.13, 95% CI: 0.48–1.78). Conversely, patients with caries had an elevated risk of PD (OR = 1.79, 95% CI: 1.36–2.35). However, Streptococcus mutans, a major caries pathogen, showed a negative correlation with several key pathogens of PD. The study concluded that there is a positive correlation between PD and dental caries at both clinical and bacterial levels. Further research is needed to understand the mechanisms underlying this association and to develop innovative prevention strategies for these two prevalent oral diseases.