 On 8 July 2009, Zheng left Charlton after failing to agree a new contract with the club following its relegation to League One.On 1 September 2009, Zheng transferred to Scottish Premier League side Celtic, signing a two-year contract and becoming the second Chinese footballer to sign for the club after Du Wei.Then manager Tony Mowbray affirmed his long held admiration for Zheng and expressed his delight at the signing.