Upon his return home, Olănescu was successively named head of public works for Craiova (1869), department head at the Agriculture, Commerce and Public Works Ministry (1875), prefect of Brăila County (1876), professor of elementary and applied mechanics at the School of Bridges, Roads and Mines (1878–1880), teacher at the silviculture school outside Bucharest (1884–1885) and deputy general director of Căile Ferate Române railway (1883).
From early 1891 to late 1895, he served as Public Works Minister in the two successive PC cabinets of Ion Emanuel Florescu and Lascăr Catargiu.
Among those approved in his second term were laws on reducing the cost of living, antitrust, tax relief for the urban poor, industry promotion, mortmain and higher education.
[4] In the autumn of 1915, Olănescu belonged to the leadership of the Unionist Federation, an organization that advocated the entry of neutral Romania into World War I, in order to unite all ethnic Romanians into a single state.
[4] In May 1918, he was among the Romanians living in Paris who signed a document denouncing the Treaty of Bucharest, through which Germany imposed a harsh peace on Romania.