The account, won after a pitch against Karen Earl, will see M&C Saatchi promote its football mobile content. The account will be headed by sponsorship managing director Steve Martin.
The mobile content will allow fans of both teams to watch highlights, receive match reviews, player interviews and alerts, and take part in competitions.
Martin’s team is also handling ticketing, hospitality and events at each club in relation to Orange’s link-up.
Orange UK PR, sponsorship and events manager Niamh Byrne said: ‘We’re partnering with Chelsea and Manchester City as mobile partners. This is not just a sponsorship deal.’
Link-ups with other Premiership clubs are currently being negotiated.
In other Orange news, the responsibilities of press officer Sally Quigg, who quit in July, have been passed to David McDonald.