A ban on working overtime for seven days has been voted for by engineers on the Tube network.
Metronet employees have been balloted
The action, voted for by 750 to 60 Rail, Maritime and Transport (RMT) members, will "eventually paralyse the system", union leaders warned.
The RMT is angry at plans by maintenance firm Metronet to transfer staff into parent firms, and said the action will start on Easter Monday.
Metronet has said any industrial action would be unjustified and unwarranted.
It said discussions were ongoing.
Metronet is the consortium responsible for maintaining and upgrading parts of the Tube.
The RMT said the firm planned to break an earlier agreement by transferring workers to its parent firms.
More than two-thirds of the Tube system would be crippled following the action of more than 2,000 engineers from April 9, union leaders warned.
RMT general secretary Bob Crow said: "Our members have demonstrated their anger at Metronet reneging on an agreement they made only a year or so ago.
"This dispute is about honouring agreements and defending our members' pay, conditions and organisation
"It is also about resisting dangerous fragmentation that our members already have too much bitter experience of."
He added: "It will have an immediate effect on traffic on two-thirds of the network, and will eventually completely paralyse the system."
Metronet said action was "not necessary" and said it had not gone back on a deal with unions.
Metronet's senior vice president Mark Cooper said: "Metronet and Bombardier have made ground-breaking compromises in order to put forward a viable alternative plan.
"We have been working for more than a year to resolve this issue and will continue to work with the RMT to find an acceptable solution."