Unite represents 26 out of the total of 55 neighbourhood managers – who deal with resident welfare and support – at the five housing association sites in central, east and south-east London.
The Peabody Trust is the parent body for the housing association’s various subsidiaries, which include the registered charity the Peabody Community Foundation.
The union members are concerned about new contracts that require evening and weekend work anywhere in the UK and training outside working hours without additional pay or time off in lieu, Unite said.
It said the new contracts would also allow cases of serious anti-social behaviour to be allocated to neighbourhood managers without adequate training and risk assessments.
Third Sector understands that the number of managers at the five sites was reduced from 80 to 55 in a recent restructuring process.
The ballot will open on Wednesday and members will be able to vote until Wednesday 27 November.
Tabusam Ahmed, regional officer at Unite, said: "The neighbourhood managers do vital work in ensuring the smooth-running of the Peabody Trust 24/7. They deal with all that comes their way, from stabbings to a lost fob.
"What the management has now imposed on our members is a major erosion in their employment conditions, without serious consultation with Unite.
"We regard the management’s stance as high-handed and this has now resulted in a strike ballot by Unite’s 26 managers.
"Once again, we urge the management to come to the table for constructive talks."
A spokesman for the Peabody Trust said discussions were ongoing, but declined to comment further.
This is the second time in a year that Unite members at the trust have voted over strike action. According to Unite, in December a vote to strike allowed staff in a central London site to gain improved terms during a transfer to Pitsea in Essex.