The union has not yet finalised dates, but said any action will begin after 21 December. Unite representatives will meet shortly to discuss dates.
It comes after crew rejected a pay rise offer of two per cent.
More than 2,000 workers were balloted on the action, which will take place at Heathrow Airport. Of those who took part, 79 per cent voted for industrial action. Mixed Fleet Unite represents about 15 per cent of British Airways' cabin crew.
Since 2010, salaries of new BA cabin crew employees joining the Mixed Fleet have been advertised at £21,000-£25,000. However, Unite said "in reality", salaries of Mixed Fleet crew, who fly a range of short and long haul routes start at just over £12,000 plus £3 an hour flying pay.
A British Airways spokesperson said:
We are extremely disappointed that the union is creating uncertainty for our customers.
We remain focused on resolving this issue as quickly as possible without any disruption to customers.
We have proposed a fair and reasonable pay increase to Mixed Fleet cabin crew which is in line with that accepted by other British Airways colleagues and which will ensure their reward levels remain in line with cabin crew at our airline competitors.
Unite said it was urging the airline to return to the negotiating table otherwise crew could go on strike after the 21 December.
Unite regional officer Matt Smith said: "Our members have overwhelmingly voted for strike action because British Airways’ pay rates are indefensible and the crew are at breaking point."
He added: "Mixed fleet crew earn just over the minimum wage and below the national average. Significant numbers of crew are taking on second jobs, many go to work unfit to fly because they can’t afford to be sick. British Airways bosses need to wake up to the anger and the injustice here."