KMT-2021-BLG-0909L is a Sun-like G-type star (about 0.38 solar masses, 5,778 K), 6,480 light-years from Earth. KMT-2021-BLG-0909L b is a 1.26-Jupiter-mass companion, at 1.750 AU from its star, discovered in 2023 via microlensing. Microlensing detections occur when a foreground star's gravity briefly magnifies a background source, revealing planets that are otherwise too faint and distant to observe directly. KMT-2021-BLG-0909L b orbits at roughly the distance of Mars from the Sun. At roughly 6,480 light-years, KMT-2021-BLG-0909L lies far beyond the nearest stars yet remains reachable to large survey telescopes.