Following cabin crews' acceptance last week of a new contract, the pilots' approval by 78.2 percent in a referendum removes the last obstacle to the creation of Boost.
The biggest pilots' union, the SNPL, announced the result in a statement Monday and said it would sign the deal "in the next few hours".
Air France said in a statement it would go ahead with the launch in the autumn, as originally planned.
In an attempt to save some loss-making routes, the company plans to cut prices by 15-18 percent.
Boost will have 28 planes.
The deal accepted by the pilots outlines savings of 40 million euros a year in the French arm of Air France-KLM.