As such, he was one of Roman Dmowski's envoys to assure English politicians that Józef Piłsudski's Polish Legions had sided with the Central Powers in order to combat Russia, not the West.

After the May Coup d'État of 1926 he sided with the camp of Marshal Józef Piłsudski and, until 1932, held the post of minister of foreign affairs in two subsequent governments.

[4] In talks with the Secretary-General Sir Eric Drummond, in exchange for an undertaking that Poland would not send the Wicher back to Danzig when the German battleship Schlesien was scheduled to visit, a confrontation that would potentially cause a German-Polish war, Zaleski wanted the League to pressure the Free City to resolve the port d'attache issue governing the right of the Polish Navy to use Danzig harbour and managed to obtain a resolution satisfactory to Poland.

[4] Zaleski's offer was taken and Drummond successfully pressured the Free City into settling the port d'attache issue in a manner favourable to Poland.

In November 2022, the remains of Zaleski, Ostrowski, and Władysław Raczkiewicz, and were moved from the cemetery at Newark-on-Trent in England to the mausoleum for emigree presidents at the Temple of Divine Providence in Warsaw.

[5] Zaleski's papers pertaining to his diplomatic work and Polish life during and after World War II are held in the collection of the Hoover Institution.