He was left fatherless at an early age and he was sent to Russia to the care of the Tsar's Minister of Foreign Affairs, Count Nesselrode, who appears in some sources is mentioned as his uncle.

[2] On 19 January 1822 he disembarked with his relatives, Emmanuel and Nikolaos Kallergis, and the officer Valianos in Hydra bringing with them ammunitions, whose worth was 100.000 rubles and a recommendation letter of bishop Ignatius Oungrovlachias.

[7] On 30 January 1827 he took part in the victorious Battle of Kastella where he had significant contributions and on 20 February he defended strongly the area of the Three Towers, which was eventually conquered by the Ottomans but she had suffered several losses.

[15] In 1834, during the Bavarian regency and the Kolettis government he was imprisoned as a supporter of the Russian Party, whose significant members had made at that time various uprisings in the Greek territory.

[2] In 1854, during the Crimean War, he served as Minister of Military Affairs in the Alexandros Mavrokordatos cabinet—imposed by the British and French, and hence called "Ministry of Occupation" by the Greeks.

This particular government recalled all the Greek officers who participated in the anti-Ottoman revolutionary movements in Thessaly, Epirus and Macedonia to return to Greece while by personal requirement of Kallergis, Otto's adjutants—Gennaios Kolokotronis, Spyromilios, Ioannis Mamouris and Gardikiotis Grivas—were dismissed, while the hitherto Minister of Military Affairs, Skarlatos Soutsos, was suspended.

[19] In 1861 he was appointed minister plenipotentiary in Paris, in which capacity he took an important part in the negotiations which followed the fall of the Bavarian dynasty and led to the accession of Prince George of Denmark to the Greek throne.

[15] In January 1867 he was appointed as Ambassador of Greece to the United States but during the trip he fell ill in Paris and returned to Athens, where he died on 8 April 1867 of hemiplegia.