Some 37,500 passengers would be hit by the nine-hour strike scheduled to begin at 0630 GMT and affecting the Frankfurt and Duesseldorf airports, Lufthansa said in a statement.
The 290 canceled flights include 23 inter-continental services, the statement said.
Lufthansa subsidiaries Germanwings, Eurowings, Lufthansa CityLine, SWISS, Austrian Airlines, Air Dolomiti and Brussels Airlines were expressly not targeted by the industrial action.
Lufthansa said it "regretted" the decision by the flight attendants' union UFO to stage a walkout between 0630 GMT and 2200 GMT at the Frankfurt and Duesseldorf airports.
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"We will do everything possible to keep disruption to a minimum," it said.
The union plans to stagger the walkouts and target different airports over the course of the next seven days, with a repeat of the stoppages planned in Frankfurt and Duesseldorf tomorrow.
However, Lufthansa's Munich hub would not be affected at all this weekend, given that there were still school holidays in the southern regional states of Bavaria and Baden-Wuerttemberg, it explained.
UFO had announced yesterday that industrial action was "unavoidable" after management had failed to come up with an improved offer in a long-running dispute over pay and early retirement provisions.