Abstract‘FL4XR16’ (Reg. no. CV‐289, PI 699961) tetraploid forage‐type annual ryegrass (Lolium multiflorum Lam.) is a synthetic cultivar selected for mid‐late maturity, high dry matter (DM) yield, and resistance to gray leaf spot (GLS). In spring 2016, a nursery of ‘FL Red’ experienced a high incidence of GLS, and 50 highly disease resistant individual plants were replanted and intercrossed. Seed from this intercross was used to establish a half‐sib nursery in fall 2016. The nursery was subsequently rogued for uniform maturity, and the remaining plants were allowed to intercross to produce the base population FL4XR16 in spring 2017. The base population went through one additional cycle of selection for uniformity. Seed harvested from this final selection cycle or a later isolated increase of this population was used to establish DM yield experiments at Citra, FL, and Tifton, GA, in 2018–2019; at Hague, FL, and Tifton in 2019–2020; and at Hague in 2020–2021 for a total of five location‐years. FL4XR16 was not significantly different in DM yield from the top entry in a given test in four of these five experiments. Maturity ratings at Gainesville, FL, show that FL4XR16 was mid‐late in maturity. The locations of evaluation for this cultivar have primarily been in the Coastal Plains region of the United States, but considering its pedigree, it is expected to perform well across the southern U.S. annual ryegrass growing region. Production and marketing rights for FL4XR16 have been granted to Smith Seed Services, Halsey, OR.