Kimchi is a traditional Korean fermented food produced through spontaneous and complex microbial fermentation, which generates diverse organic acids, flavor-active compounds, and functional metabolites. However, Spontaneous fermentation is highly sensitive to the initial microbial community and environmental factors, resulting in inconsistent product quality. This study aimed to identify optimal co-culture starter combinations that simultaneously enhance both the flavor and functional properties of kimchi. Four flavor-associated lactic acid bacteria(LAB)— Leuconostoc mesenteroides HanM48, Lactiplantibacillus plantarum DRC 2401, Lactococcus lactis DRC 2505, and Lactiplantibacillus curvatus DRC 2305—were paired with four function-associated LAB strains— Lactococcus lactis CBA3619, Loigolactobacillus coryniformisCBA3616, Lacticaseibacillus paracasei CBA3611, and Leuconostoc mesenteroidesCBA3656—to generate 16 co-culture groups, which were compared with 8 monoculture groups. The kimchi model system was inoculated with each strain or combination, and fermentation characteristics were assessed by monitoring pH, total acidity, and viable cell counts. Metabolite profiling using GC–MS revealed production patterns of flavor metabolites such as mannitol, glutamic acid, and lactic acid. Additionally, 16S rRNA sequencing was employed to evaluate microbial dynamics and strain–strain interactions under co-culture conditions. These findings provide foundational insight for developing optimized co-culture starter systems that improve both quality consistency and functional attributes in industrial kimchi production.