Mureș County (Romanian pronunciation: [ˈmureʃ], Romanian: Județul Mureș, Hungarian: Maros megye) is a county (județ) of Romania, in the historical region of Transylvania, with the administrative centre in Târgu Mureș. The county was established in 1968, after the administrative reorganization that re-introduced the historical județ (county) system, still used today. This reform eliminated the previous Mureș-Magyar Autonomous Region, which had been created in 1952 within the People's Republic of Romania. Mureș County has a vibrant multicultural fabric that includes Hungarian-speaking Székelys and Transylvanian Saxons, with a rich heritage of fortified churches and towns.

In Hungarian, it is known as Maros megye ([ˈmɒroʃ ˈmɛɟɛ]), and in German as Kreis Mieresch. Under Kingdom of Hungary, a county with a similar name (Maros-Torda County, Romanian: Comitatul Mureş-Turda) was created in 1876. There was a county with the same name under the Kingdom of Romania, and a Mureș-Magyar Autonomous Region (1960–1968) under the Socialist Republic of Romania.

The county has a total area of 6,714 km² (2,592 sq mi).

The northeastern side of the county consists of the Călimani and Gurghiu Mountains and the sub-Carpathian hills, members of the Inner Eastern Carpathians. The rest of the county is part of the Transylvanian Plateau, with deep but wide valleys.

The main river crossing in the county is the Mureș River. The Târnava Mare River and the Târnava Mică River also cross the county.

Mureș County is bordered by seven other counties: Suceava, Harghita, Brașov, Sibiu, Alba, Cluj and Bistrița-Năsăud.

In 2022, the population of Mureș County was registered as 518,193 people, 22,39% of them living in Târgu Mureș, making it the sixteenth largest city in Romania, with a population of 116,033 people.

The next city in the county by number of people is Reghin, with 29,742 people, followed by Sighișoara, with 23,927 and then Târnăveni, with 20,604.