Charles was the second son of William VI, Landgrave of Hesse-Kassel and Hedwig Sophia of Brandenburg. Until 1675 his mother ruled as his guardian and regent before Charles was old enough to take over the administration for the next 5 years. His older brother, William VII, had died in 1670 shortly after reaching adulthood, even before he had had the chance to make any changes with the administration.
Policies
Under the reign of Charles, the consequences of the Thirty Years' War in the agricultural county could be overcome more quickly than they were in the more industrialized regions of the Holy Roman Empire. He pushed for the recreation of a large army and put it in the service of other countries in the War of Spanish Succession. His soldiers, he gave, as well as other princes of his time, to foreign service for the Subsidiengelder . This policy remained controversial for its dealings with the mercenaries, according to the 1908 Brockhaus :
"Dieses System verbesserte die Finanzen, aber nicht den Wohlstand des Landes, und brachte den glänzenden Hof selbst in ausländische Familienverbindungen."
Charles left in 1685 to his younger brother Philipp as the latter's Paragium a small part of the Landgraviate of Hesse, the so-called Landgraviate of Hesse–Philippsthal, named after Philippsthal a place near Vacha on the Werra River.
Economy
Even before the Edict of Fontainebleau, Charles adopted on 18 April 1685 the , promising the exiles from France, the Huguenots and Waldensians, free settlement and their own churches and schools. In the following years, about 4000 the Protestants fled persecution in their homelands for Northern Hesse and, for example, about 1700 of them settled in :de:Oberneustadt |Oberneustadt, the newly created borough of Kassel. Following the ideas of mercantilism, Charles founded in 1679 the :de:Messinghof |Messinghof, one of the first metal-processing plants in Hesse, in :de:Bettenhausen |Bettenhausen, east of Kassel. In 1699 Charles founded Sieburg and also moved some of the Huguenots and Waldensians there. With the construction of the Landgrave-Carl-Canal from the Diemel River to Kassel, he tried to circumvent the existing customs borders but, after only a few kilometers, the construction was discontinued.
Culture
Landgrave Charles continued the design of the hillside park, Wilhelmshöhe in the Habichtswald, now a nature preserve west of Kassel. In particular, it was the construction of the Hercules monument that brought the Italian-inspired cascades and other water features to the park. Under his rule, the Moritzaue park near the town was extended over a large area to another park, the Karlsaue, which still exists today, and the SchlossOrangerie was built. With the participation of the Landgrave, who was interested in history, the first archaeological excavations began in 1709 on the :de:Mader Heide|Mader Heide.
After the death of his wife in 1713, Charles had a relationship with Jeanne Marguerite de Frere, Marquise de Langallerie, with whom he had a son, Charles Frederic Philippe de Gentil, Marquis de Langallerie, who died early. Charles secured in the same way the financial security of children who had come with his mistress. After the Marquise de Langallerie, the next mistress and confidante was Barbara Christine von Bernhold, who rose to Großhofmeisterin under Charles's son William VIII and in 1742 ennobled by the Holy Roman EmperorCharles VII to the rank of Reichsgrafin. She was housed in the Bellevue Palace.