KMT-2021-BLG-1077L is a cool M-dwarf (about 0.14 solar masses, 5,778 K), 8,240 light-years from Earth. KMT-2021-BLG-1077L c is a 0.25-Jupiter-mass companion, at 0.930 AU from its star, discovered in 2022 via microlensing. KMT-2021-BLG-1077L b is a 0.22-Jupiter-mass companion, at 1.260 AU from its star, discovered in 2022 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. Mutual gravitational tugs between the planets can slowly reshape their orbits, preserving clues to the system's assembly.