The aim of this study was to examine the effect of core exercises on swimmers Functional Movement Screen (FMS) test scores and swimming performance. A total of 32 volunteer children aged 12-15 participated in this study. Participants were separated into 3 main groups: the control group (CG; N = 10) that did not perform any exercises, the swimming group that only performed swimming training (SG; N = 11), and the core exercise training group (TG; N = 11) that performed core exercises in addition to swimming training. The functional movement patterns of the children were determined by the FMS test, and their swimming performances of 50 meters and 100 meters were measured by means of a stopwatch. The Wilcoxon Signed Ranks test was utilized to determine the ingroup difference between the pre-tests and post-tests of the children's FMS scores and swimming performances. According to the statistical analysis results, it was observed that swimming training increased FMS total score and active straight leg raising test score. Besides, core exercises significantly increased all FMS sub-tests and total score values in the post-test. At the end of the study, although there was no significant difference between pre and posttests in SG both 50m and 100m swimming performances, statistical results also proved that the 100m swimming performances of the TG increased significantly in the post-test (p < 0.05). As a result, it can be stated that the swimmers', who performs core exercises, swimming performance increased, and improved FMS test scores, which is a significant element regarding the decrease in sports injury.