Galezowski was born in Lipowice, Poland. He earned a degree in medicine from the University of St. Petersburg in 1858 and received a gold medal for his thesis on the ophthalmoscope. After moving to Paris and studying ophthalmology with Louis-Auguste Desmarres, Galezowski earned another medical degree from the Medical Faculty of Paris.
Galezowski opened his private ophthalmologic clinic in Paris in 1867. As one of the first private practitioners of his specialty, and due to his skill, Gazelowski's public reputation grew and his clinic treated an average of 8800 patients per year. Galezowski created the Journal d'Ophtalmologie (later the Recueil d'Ophtalmologie) in 1872 -- the first French journal of ophthalmology. Among his patients was Paul Lafargue, who spoke admiringly of Galezowski's work in a letter to Friedrich Engels, who also suffered from tear duct problems, dated July 28, 1887.