 Humphreys was educated at Shrewsbury School and at Trinity Hall, Cambridge, graduating BA in 1889.He was called to the Bar from the Inner Temple in 1889 and entered the chambers of E. T. E. Besley, where he concentrated on practice in the criminal courts.On 1 March 1895 Oscar Wilde, Lord Alfred Douglas and Robbie Ross approached Charles Octavius Humphreys with the intention of suing the Marquess of Queensberry, Douglas' father, for criminal libel.