At fourteen Walewski refused to enter the Russian army, escaping to London and thence to Paris, where the French government refused his extradition to the Russian authorities. Louis Philippe sent him to Poland in 1830, and he was then entrusted by the leaders of the Polish revolution with a mission to London.
After the fall of Warsaw he took out letters of naturalization in France and entered the French army, seeing some service in Algeria. In 1837 he resigned his commission and began to write for the stage and for the press. He is said to have collaborated with the elder Dumas in Mademoiselle de Belle-Isle, and a comedy of his, L'Ecole du monde, was produced at the Theâtre Français in 1840.
In that year his paper, Le Messager des chambres, was taken over by Thiers, who sent him on a mission to Egypt, and under the Guizot ministry he was sent to Buenos Aires to co-operate with the British minister Lord Howden (Sir J Caradoc). The accession of Louis Napoleon to the supreme power in France guaranteed his career. He was sent as envoy extraordinary to Florence, to Naples and then to London, where he announced the coup d'état to Palmerston.
In 1855 Walewski succeeded Drouyn de Lhuys as minister of foreign affairs, and acted as French plenipotentiary at the Congress of Paris next year. When he left the Foreign Office in 1860 it was to become minister of state, an office which he held until 1863. Senator from 1855 to 1865, he entered the Corps Legislatif in 1865, and was installed, by the emperor's interest, as president of the Chamber. A revolt against his authority two years later sent him back to the Senate. He died at Strassburg on the 27th of October 1868. He had been created a duke in 1866, was a member of the Academy of Fine Arts and a grand cross of the Legion of Honour.
He married Catharine Caroline Montagu, daughter of Earl George John Montagu and Louisa Mary Anne Hariet Corry, on 1 Dec 1831. Then married Maria Anna di Ricci, daughter of Zanobi di Ricci and Isabelle Luci, on 4 Jun 1846 in Firenze. He married a third and final time to Rachel Felix. He had seven children, two from his first, four from his second and one from his third. Louise Marie Colonna-Walewska and George Eduard Auguste Colonna-Walewski by Catharine Caroline Montagu. Isabelle Colonna-Walewski, Charles Walewski, Elise Colonna-Walewski, and Eugenie Colonna-Walewski by Maria Anna di Ricci. Alexandre Antoine Colonna-Walewski by Rachel Felix.