TOI-620 is a cool M-dwarf (about 0.58 solar masses, 3,708 K, 0.55 solar radii), 33.0 light-years from Earth. TOI-620 b is a planet with 3.8 Earth radii, with an orbital period of 5.1 days, at 0.048 AU from its star, and an equilibrium temperature near 604 K, on an eccentric orbit (e ≈ 0.22), discovered in 2022 via transit. The planet was found when it crossed the face of its star, producing periodic dips in brightness that reveal its size and orbital period to space-based photometry.