Ernst Heinrich was the youngest son of the last King of Saxony, Frederick Augustus III, and his wife Archduchess Luise of Austria, Princess of Tuscany.

Prince Ernst Heinrich of Saxony spent his childhood in Dresden, Pillnitz, and Moritzburg under the parenting of his father.

Beginning in May 1918, he led the 1st Squadron of Mounted Guard Regiments in Stary Bychow at Dnieper in Russia and, in August of the same year, he was in charge of the Saxon troops in Dorpat, Reval and Finland.

His father also gave him power of attorney to negotiate with the Free State of Saxony about the future use of the manors owned by the Wettin family and their art collection.

In subsequent years, Ernst Heinrich, who was an avid art lover, made several trips to Egypt with his wife and children.

In 1928/29, he was approached by Gustav Stresemann of the DVP (the German People's Party), who wanted Ernst Heinrich to stand as a candidate for the federal presidency.

He believed that Hitler could be stopped by the conservative political opposition and, in the spring of 1933, he joined Der Stahlhelm, hoping he could escape the influence of the Nazis.

In 1938, he received King Carol II of Romania in his castle, and in 1939 he had extensive political discussions with Carl Friedrich Goerdeler, who had been mayor of Leipzig and was later active in the German resistance.

A few weeks before the outbreak of World War II, Ernst Heinrich was drafted into the Abwehr group IV in Dresden.

After she lost her home when Berlin was bombed in 1943, he invited her to move to Moritzburg, where she lived and worked at the Rudenhof, a mansion in the immediate vicinity of the castle, until she died in April 1945.

Later that year, he purchased the Coolamber estate in Lismacaffrey (County Westmeath) in Ireland and moved there with his second wife and his sons from his first marriage.