The research from the public services trade union found 36% of 3,513 staff surveyed said staff shortages in their workplace occurred most days or every week, and 43% said this was due to staff leaving and not being replaced.
More than a third (38%) of male staff and 29% of female staff said they had witnessed job losses, making job security being the most important issue for local government employees.
Unison's head of local government, Heather Wakefield, said: "Local government employers need to realise morale is at an all-time low. Staff and services are already stretched to breaking point."
The research comes just weeks after a 0.5% pay deal for council workers in England, Wales and Northern Ireland was rejected. Wakefield added: "It is time to finally recognise the vital role local government staff play in our society with better pay."
But Dean Shoesmith, HR director at Sutton and Merton Councils and vice president of the Public Sector People Managers Association (PPMA), told HR magazine: "I would question this research because Unison is not representative of all local government employees.
"We just carried out research into satisfaction in the two councils I work for and found staff satisfaction to be increasing. We do listen to staff concerns and take action where we can. But there is more to satisfaction than pay in isolation. Employees do recognise we are in a bad recession and take that into account."
Council staff's morale is at rock bottom, claims Unison
Employee morale is at "an all-time low" in local government, with 60% of staff saying it has got worse in the past year and only 50% saying they would recommend their jobs to others, according to Unison.
