The third-generation Mercedes-Benz CLS (C257) debuted at the Los Angeles Auto Show in November 2017 and remained in production from 2018 until August 2023. Based on the modular MRA platform shared with the E-Class W213, the C257 introduced a minimalist exterior language with reduced character lines, a forward-leaning grille, and sharp angular LED lights. For the first time, the CLS came standard with a five-seat interior configuration rather than four individual seats. The dashboard featured twin 12.3-inch widescreen displays.

The engine lineup shifted to new modular 3.0-liter inline-six powerplants: the M256 gasoline unit with an integrated 48-volt EQ Boost starter-alternator and the OM656 turbodiesel, along with 2.0-liter four-cylinder engines. The V8 engine was replaced by the electrified Mercedes-AMG CLS 53 mild hybrid producing 435 hp plus a temporary 22 hp electric boost. All models featured a 9G-Tronic automatic transmission and 4MATIC all-wheel drive. Production concluded in 2023 as Mercedes streamlined its coupe model portfolio.