He was born in Rudolstadt as the son of the reigning Prince of Schwarzburg-Rudolstadt, Friedrich Günther, and his second wife, Countess Helene of Reina (1835-1860).

She died three days after giving birth to Prince Sizzo and his twin sister, Princess Helene.

On 21 April 1896, Prince Sizzo's succession rights were recognised by all members of the House of Schwarzburg.

In addition, he was made a full member of the house and able to use the title of Prince of Schwarzburg.

His tenure as head of the house would not last long and less than a year later, Prince Sizzo died in Großharthau with his only son, Prince Friedrich Günther, succeeding him as head of the house and pretender to the Schwarzburg principalities.