The current study aims to evaluate the effectiveness of an intervention based on the Sport Education model, compared to an intervention based on the traditional model of Direct Instruction in children. The intervention was carried out during school hours for 18 sessions of 50-min each. The sample was made up of 146 children aged 10–12 years (M = 10.78 years; SD = 1.07 years). Participants were randomly assigned to the experimental group (n = 87) and a control group (n = 59). A quasi-experimental design with repeated pretest and posttest evaluations with the control group was implemented. The Positive and Negative Affect Scale for children and adolescents (PANASN) was used to assess the affective component of subjective well-being. The Child and Adolescent Behavior Assessment System (BASC) was used to assess psychosocial adjustment. The results showed significant improvements in the affective component of subjective well-being and a reduction in anxiety in favor of the experimental group. Our current results show the methodological and practical efficacy of a Sport Education intervention.