As Secretary of State, Olney mediated the Venezuelan crisis of 1895 and managed Cleveland's anti-expansionist policy in response to the overthrow of the Hawaiian Kingdom and the Cuban War of Independence, though both Hawaii and Cuba were annexed during the subsequent William McKinley administration.

[4] During the 1880s, Olney became one of the Boston's leading railroad attorneys[4][5] and the general counsel for Chicago, Milwaukee and St. Paul Railway.

[6] Olney was once asked by a former railroad employer if he could do something to get rid of the newly formed Interstate Commerce Commission (ICC).

[4] Olney argued that the government must prevent interference with its mails and with the general railway transportation between the states.

[8] When the legal measures failed, he advised President Cleveland to send federal troops to Chicago to quell the strike, over the objections of the Governor of Illinois.

Olney got an injunction from circuit court justices Peter S. Grosscup and William Allen Woods (both anti-union) prohibiting ARU officials from "compelling or encouraging" any impacted railroad employees "to refuse or fail to perform any of their duties."

[9] Upon the death of Secretary of State Walter Q. Gresham, Cleveland named Olney to the position on June 10, 1895.

[4] Olney quickly elevated US foreign diplomatic posts to the title of embassy, officially raising the status of the United States to one of the world's greater nations.

Brands recounts claims that Olney "responded to a daughter's indiscretion by banishing her from his home, never to see her again, although they lived in the same city for thirty years.