Civil servants in the Public and Commercial Services union are to join a co-ordinated public sector strike day on 10 July after voting to strike over pay, the union says.
PCS members, including Passport Office staff, will join striking council and school workers from the GMB union.
The National Union of Teachers and Unison are also walking out.
The PCS said living standards were being slashed, but the government said its pay restraint helped protect jobs.
The government introduced a pay freeze in 2010, and in 2012 brought in a pay cap of 1% which is still in place. The PCS is calling for a pay rise of £1,200 or 5% for all civil service and related staff.
PCS general secretary Mark Serwotka said: "Ministers praise public servants for their hard work and dedication but at the same time they are slashing their living standards.
"Instead of warm words, public sector workers need a pay rise.
"As politicians of all parties justify pay cuts by repeating the lie that there's no money around, and household incomes fall to their lowest for more than a decade, it is clear the so called economic recovery is not being felt by everyone."
With around 270,000 members, the PCS is one of the largest trade unions in the UK.
It has an existing industrial action mandate covering pay, pensions, jobs and privatisation but three in four voted in favour of further strikes.
The co-ordinated walkout is set to be the biggest strike over pay faced by this government, according to the PCS. The first joint union walkout was on 30 June 2011 and led to the mass strike on 30 November of that year.
Local government and school support workers represented by Unison, in England, Wales and Northern Ireland have also voted to strike over pay, Council and school workers represented by the GMB union have voted by three to one to walk out in July over a pay offer worth 1% to most.
The Cabinet Office said the strike "lacks authority" as the PCS was relying on a mandate for action that is more than a year old and the results of a ballot supported by less than a fifth of their members.
It said "tough decisions" were taken to address the budget deficit but the earnings of people on less than £21,000 a year were protected.
A spokesperson added: "Pay restraint protects public sector jobs, supports high-quality public services and helps put the UK's finances back on track."