In 1641, he inherited the Principality of Calenberg from his father, Duke George of Brunswick-Lüneburg, who had suddenly died.

When in 1648, he also inherited the Principality of Lüneburg from his uncle, Frederick IV, Duke of Brunswick-Lüneburg, both subdivisions were ruled in personal union.

However, Christian Louis gave Calenberg to his younger brother George William, and instead ruled the larger territory of Lüneburg at Celle Castle.

He married Sophia Dorothea, daughter of Duke Philipp of Schleswig-Holstein-Sonderburg-Glücksburg, on 9 October 1653.

Christian Louis' widow remarried and became Electress of Brandenburg as the second wife of the Great Elector.