Physical activity (PA) in preschool children (3- to 5-year olds) is characterized by short bouts of intermittent movement, generally accumulated during free play activities. Little is known about how the amount of PA or the patterns of PA accumulation are related to health in preschoolers. Ninety-six healthy preschool children (46 boys, 50 girls; 4.4 ± 0.9 years) participated in assessments of PA, body composition, health-related fitness, blood pressure, and motor proficiency. PA data were collected for 7 consecutive days using Actigraph accelerometers. PA prevalence was assessed by the amount of total and moderate-to-vigorous PA (MVPA) in min/day and as a % of wear; PA patterns were assessed by the frequency and duration of MVPA bouts and by the duration of breaks between MVPA. Younger preschoolers engaged in less PA than older preschoolers, according to measures of prevalence and patterns (p < 0.05). Girls participated in less PA, less frequent MVPA, and longer breaks between bouts of MVPA compared to boys (p ≤ 0.001, for all). Health-related fitness was higher in preschoolers who engaged in more total PA, more frequent bouts of MVPA, longer bouts of MVPA, and shorter breaks between bouts of MVPA (p < 0.05, for all). Blood pressure was higher in preschoolers taking longer breaks between bouts of MVPA (p < 0.05). Motor proficiency was poorer in preschoolers who participated in shorter bouts of MVPA (p < 0.001). Preschoolers who met current PA recommendations of 180 min of total PA and 60 min of MVPA daily had better body composition and health-related fitness, respectively, compared to their peers who did not meet recommendations (p < 0.05). To the best of our knowledge, these data are the first to provide support for new PA guidelines and to demonstrate relationships between PA and health-related fitness and blood pressure in preschoolers. Our findings indicate that PA patterns are just as important as PA prevalence in describing relationships between health measures in preschool children.