The airline had faced major disruption over the Christmas and New Year period that could have left thousands of passengers stranded over the festive period.
However, the High Court in London upheld BA’s complaint that Unite had breached industrial relations law by balloting around 1,000 staff that had left the company or were in the process of leaving.
Judge Laura Cox said the timing of the strike would have been particularly painful for passengers and company alike and risked permanent damage to the BA brand.
“A strike of this kind over the 12 days of Christmas is fundamentally more damaging to BA and the wider public than a strike taking place at almost any other time of the year,” she said.
BA cabin crew were preparing to walk out from 22 December for 12 days. About 13,000 BA staff were balloted by the Unite union, 92.5% of whom backed the strike.
In a statement, BA says: “We are delighted for our customers that the threat of a Christmas strike has been lifted by the court. It is a decision that will be welcomed by hundreds of thousands of families in the UK and around the world.”
However, the Unite union called it a “disgraceful day for democracy” and warned it would hold another ballot in early 2010.
The judge refused Unite permission to appeal, although the union can apply directly to the Court of Appeal. However, pushing through any challenge before Christmas will be difficult since the courts break on Tuesday for the holiday.
Analysts estimated the strike would have cost the airline around £30m a day, with around 1 million passengers affected and 7,000 flights grounded.
BA recently insisted it would keep its premium airline brand, OpenSkies, contrary to speculation.
Last month, chief executive of British Airways Willie Walsh denied that recent revenue raising and cost cutting initiatives are turning the airline into a low cost carrier.
The airline recently agreed to merge with Iberia to merge in a deal that will create the world’s third biggest airline, but they will retain their seperate brand identities.
Thousands of passengers are facing disruption after Scottish airline Flyglobespan fell into administration on Wednesday (16 December), leaving passengers stranded.
British train drivers on Eurostar services will strike over the next two days (18 and 19 December) in a dispute over meal allowances, but the company said it did not expect problems for travellers because Belgian and French drivers can step in.