The aims of the present study were to evaluate dietary fiber intake and associated factors in adolescents, identify food sources of the nutrient, and determine associations between indicators of dietary patterns (energy/macronutrients/micronutrients) and dietary fiber intake. A population-based cross-sectional study was conducted involving 24-hour recall data. The NOVA classification was used to determine the contribution of foods to dietary fiber intake. Reference values from the World Health Organization (≥12.5 g) and the US Institute of Medicine (14 g) per 1,000 kcal were used to assess intake. The mean intake of dietary fiber/1,000 kcal/day was 6.4 g (1.5 g of soluble fiber and 4.9 g of insoluble fiber) among the 891 adolescents. Fiber intake was low, especially among those who ate fruits, vegetables, and beans less, those who consumed soft drinks and processed meats more, and those who did not eat breakfast every day. Unprocessed/minimally processed foods provided 68.8%, 53.7%, and 72.1% of total, soluble, and insoluble fiber, respectively, whereas ultra-processed products provided 24.8%, 37.9%, and 21.0% respectively. Fiber intake was inversely associated with energy intake, fat, free sugar, and animal protein in the diet. The insufficient fiber intake underscores the need for actions that promote healthy nutrition on the individual and family levels.