This study investigated the influence of defensive player positioning on the external and internal loads experienced during small-sided transition games (TGs) and the subsequent effects on sprint and jump performance. Twenty male youth players (age 15.7 ± 0.2 years; height 175.3 ± 7.5 cm; mass 67.1 ± 6.8 kg) completed two 7-min bouts, with 2 minutes of passive recovery, of 2 vs. 2 TGs under three defensive configurations: defenders in front of attackers (TG_Front), behind attackers (TG_Behind), and parallel to attackers (TG_Parallel). During each TG, we recorded total distance covered (DC), distance covered in running (18.0–20.9 km · h⁻¹), highintensity running (21.0–23.9 km · h⁻¹), and sprinting (> 24.0 km · h⁻¹), peak speed, mechanical load, and the number of accelerations and decelerations > 1.0 m · s⁻² and > 2.5 m · s⁻². Ratings of perceived exertion (RPE) were also collected. Sprint (30 m) and countermovement jump (CMJ) tests were administered immediately before and after each session. The results showed that TG_Parallel and TG_Behind elicited significantly greater DC, distances in running, high-intensity running, and sprinting zones, mechanical load, accelerations > 2.5 m · s⁻², and RPE compared to TGFront (p < 0.05). Moreover, TGParallel produced higher DC in high-intensity running, sprinting, mechanical load, and accelerations > 2.5 m · s⁻² than TGBehind (p < 0.05). No TG format induced significant changes in sprint or CMJ performance (pre- vs. post-test, p > 0.05). These findings demonstrate that positioning defenders behind or parallel to attackers increases both external and internal loads across running, high-intensity, and sprinting zones during TGs, without compromising subsequent sprint or jump performance.