[7][8] After graduation from Heidelberg University, McLean began working at his father's newspaper, The Cincinnati Enquirer, eventually becoming editor.

[9] By the 1880s, McLean was a prominent businessperson who owned a wide variety of newspaper, real estate, and transportation holdings.

[10] In 1895, McLean purchased the New York Morning Journal, but within six months, he sold the paper to William Randolph Hearst.

In addition to his holdings, McLean was an elected director of the American Security and Trust Company and Riggs National Bank.

He was a candidate for the United States Senate in 1885 and received the Democratic Party's nomination for the Ohio governor's seat in 1899.