Background/Objectives: Problematic eating behaviours may affect food consumption and, therefore, body weight. However, these associations have not been well understood, especially among adolescents. The aim of the study was to evaluate the associations of restrained eating and disinhibited eating with diet quality and body weight status among adolescents. Methods: A cross-sectional study was conducted among 1450 primary school students aged 11–13 years (52% girls). Dietary data were collected using the food frequency questionnaire (SF-FFQ4PolishChildren®). Two diet quality scores were evaluated: (i) the pro-Healthy Diet Index (pHDI), which included vegetables, fruit, dairy products, and fish, and (ii) the non-Healthy Diet Index (nHDI), which included fast food, sweets, sweetened beverages, and energy drinks. Based on the Three-Factor Eating Questionnaire, two eating styles were identified: restrained eating (RE) and disinhibited eating (DE). Body weight status was evaluated using the body mass index (BMI) z-score and the waist-to-height ratio (WHtR). Spearman’s correlation coefficient and logistic regression analysis were used to assess the association between eating styles, diet quality, and body weight status. Results: Restrained eating was negatively correlated with nHDI (r = −0.178, p < 0.001) and positively correlated with the BMI z-score (r = 0.253, p < 0.001) and WHtR (r = 0.197, p < 0.001). Disinhibited eating was positively correlated with nHDI (r = 0.232, p < 0.001). Among adolescents with different RE and DE levels, significant differences in the mean nHDI, BMI z-score, and WHtR were found. Compared to adolescents with ‘low RE & DE’, those with ‘low RE & higher DE’ were more likely to fall in the upper than bottom tertile of nHDI (odds ratio (OR) =1.90, 95% CI: 1.29–2.81). Adolescents with ‘higher RE & low DE’ were less likely to be underweight (OR = 0.17, 95% CI: 0.06–0.49) and more likely to be overweight (OR = 2.02, 95% CI: 1.41–2.91) and to have abdominal obesity (OR = 1.79, 95% CI: 1.13–2.82). Conclusions: The findings suggest that both eating styles may be predictors of diet quality among adolescents. Body weight status was related to restrained eating, which seems to characterise mainly adolescents with overweight or obesity.