Postbiotics are functional biological compounds, such as bacterial lysates (BLs) released from probiotic bacteria. Although postbiotics exert various bioactivities, the anti-inflammatory and antibiofilm activities of BLs against oral pathogenic bacteria have not been investigated. In the present study, pretreatment with BLs extracted from Lactobacillus plantarum and L. rhamnosus GG suppressed the mRNA and protein expression levels of inflammatory mediators induced by the lipopolysaccharide (LPS) of Porphyromonas gingivalis in RAW 264.7 cells. Both BLs attenuated P. gingivalis LPS-induced phosphorylation of mitogen-activated protein kinases (MAPKs) and activation of nuclear factor-κB (NF-κB), suggesting that BLs inhibit periodontal inflammatory responses by regulating the MAPK and NF-κB signaling pathways. Moreover, both BLs interfered with biofilm formation by Streptococcus mutans; however, they did not eradicate the established S. mutans biofilm. Furthermore, both BLs downregulated gtfB, gtfC, and gtfD responsible for biofilm formation by S. mutans, suggesting that BLs reduce the synthesis of extracellular polysaccharide and thereby reduce S. mutans biofilm. Taken together, these results suggest that BLs of L. plantarum and L. rhamnosus GG can attenuate periodontal inflammation and dental caries and thus contribute to the improvement of oral health.