Three villages are administratively part of Gherla: Băiţa (formerly Chirău and Kérö in Hungarian), Silivaş (Vizszilvás) and Hăşdate.
The locality was first recorded in 1291, as a village named Gherlahida (probably derived from the Slavic word grle, meaning "ford"). The second name was Armenian, Hayakaghak, meaning "Armenian city"; it gave the Medieval Latin and Greek official name Armenopolis, as well as the German alternative name Armenierstadt. Later, the name of Szamosújvár was used in official Hungarian records, meaning "the new town on the Someş". Before 1918, Gherla was part of the Kingdom of Hungary comitatus of Szolnok-Doboka. It was again part of Hungary between 1940-1944.
The modern city was built in the early 18th century by Armenians, successors of the Cilician Armenian diaspora who had originally settled in Crimea and Moldavia and moved to Transylvania sometime after 1650. After a two years' campaign on the part of the Armenian-Catholic Bishop Oxendius Vărzărescu, they converted from the Armenian Apostolic Church to the Armenian Catholic Church.
Gherla is the seat of the Roman Catholic-led Armenian Rite Gherla Vicariate as well as that of a Greek-Catholic diocese – the Cluj-Gherla Diocese (suffragan to the Greek-Catholic Archbishop of Alba Iulia and Făgăraş-Blaj, who resided in Blaj). In the center of the city lie the Saint Gregory the Illuminator and the Holy Trinity Armenian Cathedral. The main Armenian-Catholic church was built in 1792. The Greek Catholic diocese was created through the Papal Bull Ad Apostolicam Sedem of November 26, 1853, and the first bishop was Ioan Alexi.
A Habsburg fortress was built here, and in 1785 it was transformed into a prison which, during the Communist regime, was used for political detainees. Today it is one of the high security prisons in Romania.
The town is often visited by Orthodox pilgrims on their way to the nearby village of Nicula and Nicula Monastery.