After his return to Romania in 1878, Haret abandoned scientific research and dedicated the rest of his life to improving Romanian education, which was heavily underdeveloped at the time, both as professor and as politician. He was appointed professor of rational mechanics at the Science Faculty in Bucharest. The next year (1879), Haret became a correspondent member of the Romanian Academy, receiving full membership in 1892. He kept the professorship at the Science Faculty until his retirement in 1910, when he was followed as professor of mechanics by Dimitrie Pompeiu. From 1882 he was also a professor of analytical geometry at the "Bridges and Roads' School in Bucharest". After retirement, Haret occasionally lectured at the informal "People's University".