We present Very Large Telescope/FORS2 time‐series spectroscopy of the Wolf–Rayet (WR) star #41 in the Sculptor group galaxy NGC 300. We confirm a physical association with NGC 300 X‐1, since radial velocity variations of the He iiλ4686 line indicate an orbital period of 32.3 ± 0.2 h which agrees at the 2σ level with the X‐ray period from Carpano et al. We measure a radial velocity semi‐amplitude of 267 ± 8 km s−1, from which a mass function of 2.6 ± 0.3 M⊙ is obtained. A revised spectroscopic mass for the WN‐type companion of 26+7−5 M⊙ yields a black hole mass of 20 ± 4 M⊙ for a preferred inclination of 60°–75°. If the WR star provides half of the measured visual continuum flux, a reduced WR (black hole) mass of 15+4−2.5 M⊙ (14.5+3−2.5 M⊙) would be inferred. As such, #41/NGC 300 X‐1 represents only the second extragalactic WR plus black hole binary system, after IC 10 X‐1. In addition, the compact object responsible for NGC 300 X‐1 is the second highest stellar‐mass black hole known to date, exceeded only by IC 10 X‐1.