TOI-1859 is a Sun-like F-type star (about 1.29 solar masses, 6,341 K, 1.36 solar radii), 224 light-years from Earth. TOI-1859 b is a planet with 9.8 Earth radii, with an orbital period of 63.5 days, at 0.337 AU from its star, on an eccentric orbit (e ≈ 0.57), discovered in 2023 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. The planet's marked eccentricity suggests past scattering events or perturbations from unseen companions.