Body image is a complex construct related to how each person perceives their own body and how they value it. Physical fitness and physical activity are factors that can influence the perception of a better or worse body image. This study aimed to identify the potential associations between body image and physical fitness self-perception in future Spanish teachers, analysing possible sex-related differences. A total of 278 Spanish university students answered the Multidimensional Body Self Relations Questionnaire and the International Fitness Scale, having an average age of 22 years, of which 40% were men and 60% were women. Nonparametric techniques (Spearman’s Rho test) were used as the data did not fit normality. The findings showed associations between body image and perceived physical fitness, confirming differences between the sexes. Correlations were found between the first three dimensions of the Multidimensional Body Self Relations and the International Fitness Scale, with sex-related differences being more significant in women than in men, and between the physical abilities self-assessed by the International Fitness Scale (except flexibility) and the dimensions of the Multidimensional Body Self Relations (except Dimension 4). Since body image influences well-being and conditions the time spent exercising, public health organisations and universities should design supports to improve master students’ body image through physical activity programmes, education and sex-specific individualised attention.