Almost 100,000 workers will walk out in the action, which will affect prisons, job centres and benefit agencies.
Some 90,000 staff from the department for work and pensions and 4,500 from the prisons service are planning to go on strike next Tuesday and Wednesday.
The Public and Commercial Services Union today announced that they will be joined by 1,500 from the Office for National Statistics for the first day of action.
The stoppages have been sparked by pay offers that the union said did little to address the growing problem of low wages for many civil servants.
They follow similar action by staff in the Department for Work and Pensions (DWP) earlier this year when some Job Centres and benefit offices were forced to close.
The union said thousands of workers earned less than £10,000 a year and more than 20,000 staff in the DWP had to claim the same benefits they were administering because of their low pay.
Managers in the department have said they have offered a substantial pay deal worth an average 5% aimed at junior and the worst-paid staff.
But the union said the "imposed" pay deal, rejected by its members, was worth just 2.9%. The union has also submitted the first national pay claim for the civil service in a decade.
The claim is on behalf of 300,000 workers in more than 200 government departments and agencies.
It aims to end pay inequalities and set minimum standards on pay and conditions by ending delegated pay bargaining and returning to one national pay deal.
The union's general secretary, Mark Serwotka, said: "The government says it wants a more efficient civil service, yet is happy to preside over the farce of over 200 different sets of pay negotiations.
"It is a scandal that we are still locked in disputes over last year's pay, with departmental managers happy to drive down pay and introduce discriminatory bonus schemes.
"Our national pay claim is about providing solutions to the growing problems of pay and its about bringing the civil service in line with the rest of the public sector."
· Meanwhile, talks between Network Rail and the RMT have broken down, meaning the rail union's executive is almost certain to call a strike ballot next week. The dispute is over the not-for-profit company's offer of a 3% pay deal
