The union said 97.5 percent of staff voted in favour of walk-outs in order to turn up the pressure on Lufthansa's management in the gridlocked talks. A total 83.2 percent of members participated in the ballot.
"It's a stern warning to management that they must understand how serious the situation is," UFO's chief negotiator Dirk Vogelsang told news agency AFP.
Nevertheless, no strikes would be staged for now, as Lufthansa management is seeking to table a new offer by August 16, the union added.
The union is seeking a 5.0 percent pay increase for cabin staff for 15 months starting from January this year after three years of zero increases.
It is also opposed to the use of temporary cabin staff in Lufthansa aircraft. The airline is seeking to cut costs to boost profits.
The threat of strike action was weighing on Lufthansa shares on the Frankfurt stock exchange, where they were showing a loss of 4.0 percent in a slightly weaker market.