Born Prince Leopold Franz Julius of Saxe-Coburg-Saalfeld, Duke in Saxony on 31 January 1824, he was the third son of Ferdinand, Prince of Saxe-Coburg and Gotha-Koháry and Princess Maria Antonia Koháry de Csábrág et Szitnya.

Leopold was a younger son and was unlikely to inherit titles or land, so he entered the Army in the service of the Austrian Empire.

At one point, Leopold was considered as a potential husband for Isabel II of Spain.

Because the marriage of his parents was unequal (and thus morganatic), Franz was barred from the succession of Koháry and Saxe-Coburg and Gotha.

Leopold is buried in the ducal mausoleum at Friedhof am Glockenberg [de], Coburg.