Ernst was the eldest son of Duke Ernst of Saxe-Coburg-Saalfeld and Princess Luise of Saxe-Gotha-Altenburg, the last legitimate descendant of the royal house of the same name. The age difference between the two spouses was considerable. At the time of the marriage on July 31, 1817, the bride was 16 years old, the groom 33. They were therefore very different in terms of life experience. Ernst's younger brother was Prince Albert, the later husband of the British Queen Victoria.
Ernst received extensive training in piano playing and musical theory at a very early age, which he later continued with Heinrich Carl Breidenstein in Bonn and Carl Gottlieb Reißiger in Dresden. In 1846, at the suggestion of Franz Liszt, he composed the opera "Zaire" based on the tragedy of the same name by Voltaire. This was followed by "Tony or Retribution" in 1848, "Casilda" in 1851 and his most successful and ambitious work from 1852 to 1854 with the opera "Santa Chiara".[13]
Under Ernst's patronage, the First German Gymnastics and Youth Festival was held in Coburg in July 1860, enabling the spread of the gymnastics movement that had previously been suppressed by the government[14], and in September the First General Assembly of the German National Association, founded under his spiritual patronage in 1859. In 1861 the 1st German Shooting Festival was held in Gotha and the German Shooting Association was founded, and in 1862 the German Singers' Association was founded in Coburg. In 1860 he gave the German Singers' Festival space to develop freely. His commitment to making major events for singing, gymnastics and shooting clubs possible earned him the nickname "King of Gymnasts and Shooters"
Ernst significantly expanded the art collections at Veste Coburg and Friedenstein Castle, had the Ducal Museum built in Gotha from 1864 to 1879 and was also active as a director and actor.
In 1857, Ernst II was elected a member of the Leopoldina Academy of Scholars