Robert John Lynn (14 March 1873 – 12 September 1928) was an Australian businessman and politician who served as a member of the Legislative Council of Western Australia from 1912 to 1924.

He arrived in Western Australia in 1895, during the gold rushes, and spent one year prospecting at Coolgardie before settling in Fremantle, where he worked as a clerk for a shipping firm.

They supplied capital to run-down coal leases in the Collie district, and eventually consolidated their interests into Amalgamated Collieries Ltd., which from the early 1920s had a near monopoly on the coalfields.

He entered parliament for the Liberal Party at the 1912 Legislative Council election, replacing Robert Laurie as one of the three members in West Province.

Lynn joined the newly formed Nationalist Party in 1917, and was re-elected for another six-year term the following year.