KOI-1599 is a Sun-like G-type star (about 1.02 solar masses, 5,833 K, 0.97 solar radii), 1,132 light-years from Earth. KOI-1599.02 is a 9.0-Earth-mass planet, with an orbital period of 13.6 days, at 0.112 AU from its star, discovered in 2019 via transit. KOI-1599.01 is a 4.6-Earth-mass planet, with an orbital period of 20.4 days, at 0.147 AU from its star, discovered in 2019 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.