Reduced sleep duration in schoolchildren has been associated with poor health outcomes at the scholar level; however, there is little information on the effects of sleep loss on Chilean preschoolers. The aim of this study was to describe and compare cardiometabolic outcomes according with the sleep duration in Chilean preschoolers. A second aim was to identify potential risk outcomes (i.e., in odds ratios) for suffering anthropometric and body composition alterations related with participants’ sleep duration. A total of 99 (n = 54 boys; n = 45 girls) preschoolers (mean age (95% CI) 3.1 (2.7, 3.4 years), mean weight 16.1 (15.5, 16.6 kg)) were included in this study. Sleep duration was assessed using standardized questionnaires with the parents. Socio-demographic parents’ information, as well as anthropometric, nutritional, and handgrip strength outcomes in preschoolers were distributed by tertiles (T1; < 10 h, T2; 10 to < 11 h, and T3; ≥ 11 h) of sleep time. Children in the lowest tertile of sleep duration had significantly higher body mass indices (p = 0.036), weight-for-height Z-scores (p < 0.0001), waist–hip ratios (p = 0.041), and body fat in percent (p = 0.035) and kg (p = 0.044) compared to those in the top tertile. Low sleep duration was associated with significantly greater risks of overweight/obesity (OR 1.3 (0.9, 1.8)), low height (OR 1.2 (0.8, 1.6)), and increased BMI (OR 1.5 (0.4, 1.4)), but not with reductions in grip strength. Chilean preschoolers with low sleep duration showed higher cardiometabolic markers (anthropometric/body composition) and were more likely to be classified as obese than youth with longer sleep duration.