Peacock played his entire professional career for Charlton Athletic, making over 500 Football League appearances between 1962 and 1979.
[citation needed] On 21 August 1965, he became the first substitute used in the Football League when he replaced injured goalkeeper Mick Rose after 11 minutes of an away match against Bolton Wanderers.
[3] He played for the Columbus Magic of the ASL before joining his old friend Gordon Jago as his assistant manager and player at the Tampa Bay Rowdies in the North American Soccer League until 1982.
He later served as assistant manager at Charlton Athletic before stepping down after the resignation of Alan Curbishley in 2006.
[6] On 4 January 2011, Peacock was appointed caretaker manager of Charlton following the departure of Phil Parkinson.