The former Republic of Ireland and Manchester United captain has paid the price for a run of seven defeats in nine league games which has left the club in 19th place and just three points above the relegation zone.
Keane, 39, guided Town to 15th in his first full season in charge and have a Carling Cup semi-final first leg against Arsenal at Portman Road next Wednesday after Sunday's FA Cup third-round tie at Chelsea.
First-team coach Ian McParland will take charge at Stamford Bridge.
Source: PA
Source: PA