MXB 1658-298 is a Sun-like G-type star (about 1.98 solar masses, 5,778 K). MXB 1658-298 b is a 23.7-Jupiter-mass companion, with an orbital period of 2.08 years, at 1.613 AU from its star, discovered in 2017 via eclipse timing variations. MXB 1658-298 adds another data point to the growing catalogue of planetary systems whose masses, orbits, and host-star properties constrain models of planet formation. MXB 1658-298 b orbits at roughly the distance of Mars from the Sun. At 23.7 Jupiter masses, the companion lies near the dividing line between giant planets and brown dwarfs.