RMT members contracted by Mitie will walk out on 16, 18, 20 and 23 December in a dispute over pay.
It comes after members returned an 81% vote in favour of strike action after rejecting a below inflation pay offer.
The RMT said some workers were earning as little as £10.66 an hour.
The union warned the action would "severely affect Eurostar services and travel plans for people over the December period".
More than 100 members of Eurostar security staff employed by Mitie 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."
TTG has approached Mitie for comment.
’Disappointing blow’
Clive Wratten, chief executive of the Business Travel Association, said the strikes came as another "disappointing blow" to business travellers.
"We urge the government and the unions to come to a better conclusion so travel may get back on track ahead of a busy Christmas period."
