RMT members working as security staff for Eurostar will walkout on the 16,18,22 and 23 of December in a dispute over pay.
The workers, some of whom earn as little as £10.66 per hour rejected a below inflation pay offer and emphatically voted for strike action with an 81% 'yes' vote.
The strike action will severely affect Eurostar services and travel plans for people over the December period.
Security staff perform essential duties of keeping passengers safe during international rail travel and are contracted out to facilities management company Mitie.
Mitie made £50m in profit between March and September this year.
Over 100 staff are expected to take part in the action.
RMT general secretary Mick Lynch said: "Eurostar security staff are essential to the running of Eurostar, and it is disgraceful they are not being paid a decent wage.
"They work long unsocial hours and a multimillion-pound company like Mitie can easily afford to pay them decently for the essential work they do.
"We do not want to disrupt people's travel plans, but our members need a pay rise, and this is the only way management will listen.
"I urge Mitie and Eurostar to come to a negotiated settlement with RMT as soon as possible."