Background: This study describes the prevalence, frequency, and type of physical activity and sport (PAS) practiced by trans persons before and after their gender disclosure (GD). Methods: A face-to-face survey was administered to 212 Spanish trans persons, aged from 10 to 62 years old. McNemar and chi-square tests were used to determine significant differences. Results: About 75.5% of the trans persons in this study engaged in PAS and more than 50% did so ≥3 times/week, which is similar as in the general Spanish population. Participation was higher in trans men (78.7%) than trans women (72%). However, GD emerges as a key issue in characterizing trans persons’ PAS participation. A group of 14.5% of them stopped activity after GD. Participation in nonorganized PAS was higher than in organized PAS, and this difference is greater after GD because most participants gave up organized PAS in favor of nonorganized PAS. Trans persons preferred individual sports and activities than team sports before and after GD, and the top 3 activities were jogging, walking, and bodybuilding. Trans men participation was higher than trans women in team PAS, whereas individual PAS were equally practiced before and after GD. Participation in football, swimming, basketball, dancing, and volleyball declined after GD, whereas bodybuilding increased in trans men. Conclusions: The results show that the high involvement of trans persons coincides with strategies used to hide or conceal their gender identities when participating in PAS. A decrease in PAS participation is observed after GD probably because it is an acute potential period of anxiety, discrimination, and victimization caused by trans persons’ body exposure.