The Curve, which will house a new library, learning, arts, performance and community facilities, was scheduled to be completed for December 2015.
However, a council statement said the centre will not be handed over by Morgan Sindall until February, with the opening deferred until spring 2016.
In a meeting with council directors and commissioners, Pat Boyle, managing director construction for Morgan Sindall, explained the delay was due to an underestimation of the amount of work still required to hand over the building.
He said: “I would like to apologise sincerely for the disappointment and inconvenience a delay to the project will cause.
“I can assure you Morgan Sindall will ensure the completion of the project remains its top priority and the building will be one which Slough can be proud of.”
Morgan Sindall has promised to cover expenses the council will incur due to the delay.
Martin Carter, commissioner for community and leisure, said: “The Curve is unique and innovative with a dynamic design and it is very important to us it is delivered to residents with the quality we expect.
“I am still incredibly excited by the new opportunities this building will afford to all residents in terms of leisure, culture and the arts.”