[1] On 21 December 1524, the school was founded by Friedrich Myconius, a friend of Martin Luther, in the cloister of the Augustinian monastery of Gotha, which was in the process of being dissolved,[1] and was given the Latin name Gymnasium Gothanum.

[2] As a result of the Reformation, in the middle of the 16th century the curriculum was changed significantly, under the direction of Cyriacus Lindemann [de] (1562–1568).

He gave asylum to sons of persecuted Lutherans from Hungary, Silesia, Poland, Russia, and Scandinavia, who joined the school.

Under Johann Gottfried Geißler as rector (1768–1779), the time given to ancient languages was reduced in favour of the natural sciences and German, English, and French literature.

However, the school was challenged by a new competitor, founded in 1836 by the reigning Duke for the benefit of the bourgeoisie, the Real-gymnasium Ernestinum, which had a chiefly scientific and mathematical curriculum.

At the older school, chemistry, physics, and geology began to be taught as separate subjects, and the modern languages French and English overtook Latin in importance.

[11] A new rector, Otto Küttler (1938–1945), took the school through the Second World War, when it suffered from masters and boys departing on military service.

[6] On 1 November 1991, following German reunification, the Ernestine Gymnasium was re-established,[12] with Lutz Wagner as Schulleiter, or Principal, and in 1993 the first Abitur examinations took place, after a gap of 48 years.