The study aimed to investigate the association of varying body mass index (BMI) with oral health status among children aged 5–14 years and correlate the concentration of salivary levels of 1,5-AG with varying BMI, dental caries, and periodontal disease. This cross-sectional study was conducted on subjects aged 5 to 14 years. The children were recruited from the Pediatric Dental Clinic, College of Dentistry, Majmaah University, by convenient sampling method. Sociodemographic details and clinical parameters, including body mass index (BMI), DMFT/def (deciduous decayed tooth (d), deciduous extracted tooth (e), deciduous filled tooth (f), permanent tooth decayed (D), permanent missing tooth (M), and permanent filled tooth (F)), plaque index (PI), and modified sulcular bleeding index (mSBI), were evaluated. Salivary 1,5-anhydroglucitol (1,5-AG) was analyzed using an enzyme-linked immunosorbent assay (ELISA) for all the subjects. Statistical analyses performed using SPSS v. 27 (IBM Statistics, Chicago, IL, USA) and the Kruskal–Wallis and chi-square tests were used for comparisons. The Spearman rank correlation coefficient was used to examine the association between the study subjects’ independent variables, BMI, and caries activity. The mean def score, PI, and mSBI scores were higher in obese children. PI score, mSBI score, and salivary concentrations of 1,5-AG between the BMI categories were statistically significant (p < 0.001). The study emphasizes promoting preventive oral health regimes, health awareness campaigns, and nutritional educational programs among the pediatric population.