Kepler-1921 is a Sun-like F-type star (about 1.25 solar masses, 6,120 K, 2.00 solar radii), 929 light-years from Earth. Kepler-1921 c is a planet with 1.4 Earth radii, with an orbital period of 3.2 days, at 0.045 AU from its star, and an equilibrium temperature near 1,791 K, discovered in 2023 via transit. Kepler-1921 b is a planet with 2.9 Earth radii, with an orbital period of 20.0 days, discovered in 2021 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.