Christian Wilhelm was a son of Elector Joachim Frederick of Brandenburg (1546-1608) from his first marriage with Catherine (1549-1602), a daughter of Margrave John of Brandenburg-Küstrin (1513-1571).

Under the Peace of Prague of 1635, he received an annual sum of 12000 taler from the revenues of the archbishopric of Magdeburg, plus the districts Loburg and Zinna.

His first wedding took place on 1 January 1615 in Wolfenbüttel, where he married Dorothea (1596-1643), a daughter of the Duke Henry Julius of Brunswick-Wolfenbüttel.

On 22 February 1650 in Prague, he married Barbara Eusebia (d. 1656), a daughter of Count Jaroslav Borzita of Martinice and his first wife, Maria Eusebie von Sternberg.

On 28 May 1657, he married, again in Prague, to Countess Maximiliane (1608-1663), daughter of Count Weichard of Salm-Neuburg and Sidonia von Minckwitz.