During most of his life, John stood little chance of inheriting the Saxon Crown: he was preceded by his father and two older brothers, Frederick Augustus and Clement. However, in 1822 Clement died unmarried in Italy, and John was now only preceded in the line of succession by his older brother Frederick Augustus. When his uncle Anton succeeded his older brother as king, John became the third in line to the throne, and after his father Maximilian renounced his succession rights in 1830, John became in the second in line. John's older brother became King Frederick Augustus II in 1836; now he was the first in line of succession to the throne. The King, married twice, was childless. John remained as heir presumptive during all the reign of his brother.
John became King of Saxony after the death of his brother Frederick Augustus II on 9 August 1854. The Judiciary Organization of 1855, the extension of the railroad network, the introduction of the freedom of trade are attributed mainly to his suggestion and promotion. Under his government, came the acceptance of the French Commercial Treaty and the acknowledgment of a contract with Italy. He exerted himself under influence of his minister Friedrich Ferdinand von Beust for the Great Germany Solution of the imperial arrangement. In 1866 Saxony fought on the Austrian side in the Austro-Prussian War. Finally, after the defeat of the Battle of Königgrätz, Saxony joined the North German Confederation and in 1871 the German Empire under the hegemony of the Kingdom of Prussia. The King died two years later, aged seventy-one. Beyond his political work, Johann was busy with literature. Under the pseudonym Philalethes he translated to German the Dante's Divine Comedy; some parts of this work were placed in the Schloss Weesenstein. The Dresden district of Johannstadt was named after him.
Maria Auguste Fredericka Karoline Ludovike Amalie Maximiliane Franziska Nepomucena Xaveria, known as Maria.
Frederick Augustus Albert Anton Ferdinand Joseph Karl Maria Baptist Nepomuk Wilhelm Xaver Georg Fidelis, King Albert of Saxony.
Maria Elisabeth Maximiliana Ludovika Amalie Franziska Sophia Leopoldine Anna Baptista Xaveria Nepomucena, known as Elisabeth; married firstly on 22 April 1850 to Ferdinando, Prince of Savoy and Sardinia and 1st Duke of Genoa, and secondly on 4 October 1856 to Niccolò, Marchese Rapallo.
Frederick Augustus Ernst Ferdinand Wilhelm Ludwig Anton Nepomuk Maria Baptist Xaver Vincenz, known as Ernst.
Frederick Augustus Georg Ludwig Wilhelm Maximilian Karl Maria Nepomuk Baptist Xaver Cyriacus Romanus, King Georg of Saxony.
Maria Sidonia Ludovica Mathilde Wilhelmine Auguste Xaveria Baptista Nepomucena Veronica Hyacinthia Deodata, known as Sidonia.
Anna Maria Maximiliane Stephania Karoline Johanna Luisa Xaveria Nepomucena Aloysia Benedicta,, known as Anna; married on 24 November 1856 to Ferdinand IV, Grand Duke of Tuscany.
Margarete Karoline Fredericka Cecilie Auguste Amalie Josephine Elisabeth Maria Johanna, known as Margarete; married on 4 November 1856 to Archduke Carl Ludwig of Austria, her cousin.
