Our study examined how increased dairy consumption versus habitually low dairy consumption, against a background of healthy eating (and exercise), influenced diet quality, nutrient intake, and snacking in Canadian female adolescents (14.8 ± 2.2 years) with overweight/obesity (OW/OB). We also explored dairy consumption patterns in the group consuming dairy products. Participants were randomized into two groups: higher/recommended dairy (RDa; 4 svg/d; n = 24) or low dairy (LDa; 0–2 svg/d; n = 23). Both groups participated in a 12-week, eucaloric, lifestyle modification intervention consisting of exercise training and nutritional counseling. The intervention increased the total Canadian Healthy Eating Index score (p < 0.001) with no differences between groups. The “other food” sub-score improved more in RDa than LDa (p = 0.02), and the “saturated fat” sub-score increased more in LDa than RDa (p = 0.02). The intervention significantly increased the consumption of dairy-related nutrients more in RDa than LDa (p < 0.05). The intervention also decreased snack size in both groups (p = 0.01) and improved percentage of healthy snack energy intake more in RDa than LDa (p = 0.04). More servings of dairy products were consumed as snacks than at breakfast, lunch, or dinner (p < 0.05). Thus, our study improved diet quality, and dairy product consumption improved intakes of key related nutrients and snack consumption in adolescents with OW/OB.