He was born in Wronowo on the 21st of April 1811. He completed the Warsaw Lyceum; then in 1828-1830 he studied law at the University of Warsaw. He had friendly relations with personages such as Zygmunt Krasiński, Leon Ulrich, and Konstanty Gaszyński. Koźmian took part in the November Uprising and was promoted Second Lieutenant. After the fall of the uprising he emigrated from Poland and spent many years in England. When in London, he twice received Fryderyk Chopin (in 1837 and 1848), whom he had known already during his studies at the Warsaw Lyceum. In England Koźmian collaborated with the Literary Association of the Friends of Poland and was also involved in the financial aid for Polish emigrants. He was connected with the Conservative circles of the ‘Hôtel Lambert’ camp. Following his return to the partitioned Poland (1849), together with his brother Jan Koźmian he launched the “Przegląd Poznański” magazine. He also published his literary criticism in the columns of “Gazeta Wielkiego Księstwa Poznańskiego” Koźmian translated, and commented upon, Shakespeare’s works; together with Józef Paszkowski and Leon Ulrich, with the help of Józef Ignacy Kraszewski, he published Dzieła dramatyczne Williama Shakespeare'a. He had two daughters. From 1875 he was the chairman of the Poznań Society of Friends of Learning. He died in Poznań on the 23rd of April, 1885.