Charles was married on 5 February 1735 in Eisfeld to Princess Elisabeth Albertine of Saxe-Hildburghausen, daughter of Ernest Frederick I, Duke of Saxe-Hildburghausen.  She was regent to her son in 1752 and played a major part in the struggle for the throne at that time. They had ten children, six of whom survived into adulthood:
The future king and emperor was born William Frederick Louis of Prussia (Wilhelm Friedrich Ludwig von Preußen) in the Kronprinzenpalais in Berlin on 22 March 1797. As the second son of Louise of Mecklenburg-Strelitz and Prince Frederick William , himself son of King Frederick William II , William was not expected to ascend to the throne.
Adolphus Frederick II, Duke of Mecklenburg-Strelitz: 6. Duke Charles Louis Frederick of Mecklenburg: 13. Princess Christiana Emilia Antonia of Schwarzburg-Sondershausen: 3. Princess Charlotte of Mecklenburg-Strelitz: 14. Ernest Frederick I, Duke of Saxe-Hildburghausen: 7. Princess Elisabeth Albertine of Saxe-Hildburghausen: 15.
Adolphus Frederick II, Duke of Mecklenburg-Strelitz: 6. Duke Charles Louis Frederick of Mecklenburg-Strelitz: 13. Princess Christiane Emilie of Schwarzburg-Sondershausen: 3. Princess Charlotte of Mecklenburg-Strelitz: 14. Ernest Frederick I, Duke of Saxe-Hildburghausen: 7. Princess Elisabeth Albertine of Saxe-Hildburghausen: 15.
Francis, Duke of Saxe-Coburg-Saalfeld (15 July 1750, in Coburg – 9 December 1806, in Coburg), was one of the ruling Thuringian dukes of the House of Wettin.As progenitor of a line of Coburg princes who, in the 19th and 20th centuries, ascended the thrones of several European realms, he is a patrilineal ancestor of the royal houses of Belgium, Bulgaria and Portugal, as well as of several ...
Prince Frederick, Duke of York and Albany KG GCB GCH (Frederick Augustus; 16 August 1763 – 5 January 1827) was the second son of George III, King of the United Kingdom and Hanover, and his consort Charlotte of Mecklenburg-Strelitz. A soldier by profession, from 1764 to 1803 he was Prince-Bishop of Osnabrück in the Holy Roman Empire.
12. Otto Charles Frederick, Prince of Schönburg-Waldenburg: 6. Otto Victor, Prince of Schönburg-Waldenburg: 13. Henriette Eleonore of Reuss-Köstritz: 3. Princess Mathilde of Schönburg-Waldenburg: 14. Louis Frederick II, Prince of Schwarzburg-Rudolstadt: 7. Princess Thekla of Schwarzburg-Rudolstadt: 15. Landgravine Caroline of Hesse-Homburg