The much-respected journalist died suddenly aged 52 in March.
His sister Lizzie helped unveil the bench opposite the press room with the racecourse chairman, Bridget Guerin, in a short ceremony yesterday.
Members of the media York officials and friends of Mr Richmond were also present at the ceremony on the opening day of the three-day Dante Festival.
Mrs Guerin said: “We all miss Tom so very much and can’t believe he is not here with us today.
“Racing was his hobby and he was a great ambassador for both racing and York.”
Mr Richmond’s family have chosen The Injured Jockeys Fund for donations to be made in his memory.
To donate, visit https://www.justgiving.com/fundraising/rememberingtomrichmond.