Johnson began his engineering career with the locomotive builders E.B.Wilson and Company. In 1859 he became Acting Locomotive Superintendent at the Manchester, Sheffield and Lincolnshire Railway. Following thi, in 1864, he was appointed Locomotive Superintendent of the Edinburgh and Glasgow Railway. After only two years in Scotland he replaced Robert Sinclair of the Great Eastern Railway (GER) at Stratford Works. There he stayed for seven years, until 1873, when he accepted a position with Midland Railway (MR), at Derby, where he would stay until his retirement in 1904.