McLean was elected to the Victorian Legislative Assembly in 1880 and was promoted to cabinet in 1890, serving under James Munro, William Shiels, and George Turner.

McLean was educated at the local state school, assisted his father on his stations, and for a short period was on the staff of the Gippsland Times.

[1] A conservative, he was President of the Board of Land and Works and Minister of Agriculture[1] in the James Munro ministry from 1890 to 1891, and Chief Secretary from 1891 to 1892, retaining this position under William Shiels from 1892 to 1893.

However, reassured to some degree by Deakin's composite stand as an Australian Briton, McLean sent him to London in January 1900 as Victoria's representative in negotiations with the British government.

In March 1901, however, he was elected a member of the first Australian House of Representatives for the seat of Gippsland, and sat as a supporter of the Protectionist Party of Edmund Barton and Alfred Deakin.

Watson resigned in August, and the Free Trade leader George Reid formed another minority government, supported by the conservative Protectionists.

He was twice married, once in 1866 to Margaret Bridget Shinnock of Maffra (ca.1847 – 7 August 1884), and subsequently, to Emily Macarthur (née Linton), who survived him with five sons and two daughters by the first marriage.