In three union ballots Metronet workers voted by a total of 1,369 to 70 to strike.
The transport trade unions RMT, TSSA and Unite have voted for strike action to defend jobs and conditions at failed Tube privateer Metronet.
RMT said the strike votes were sparked by the failure of the bankrupt company's administrators to provide guarantees that there will be no job losses or forced transfers as a result of the company's financial collapse.
RMT and TSSA members also voted to strike over the failure to guarantee that there would be no cuts in pension entitlements.
RMT general secretary Bob Crow said: "Our members have said with a single, united voice that they are not prepared to be made to pay for the failure of the PPP with their jobs, conditions or pensions,"
TSSA general secretary Gerry Doherty, commented: "Metronet shareholders may be able to walk away from this PPP fiasco but it is our members who are being asked to pick up the bill with lost jobs, transfers and pension cutbacks.”
He added: "They have sent a clear message today to the Administrator and the Mayor that they will not stand for it. The long-term solution must be to bring this work back in-house to the public sector."
Unite assistant general secretary Jennie Bremner said: "This 'yes' vote gives Unite the mandate to take strike action against Metronet's shameful plan to cut hundreds of jobs and outsource a further one thousand.”