The European Commission has approved Ryanair's planned acquisition of LaudaMotion without conditions.
"The Commission concluded that the transaction would raise no competition concerns in the European Economic Area," it said in a statement.
LaudaMotion is the company through which former motor racing champion Niki Lauda re-acquired in January the assets of NIKI, the leisure air carrier he founded in 2003 and which was later integrated into Air Berlin.
Ryanair agreed in March to buy a majority stake in the new Austrian leisure airline in a major push on the German and Austrian markets dominated by Lufthansa.
Ryanair had agreed to buy an initial 24.9% stake in Vienna-based LaudaMotion.
That would rise to 75% "as soon as possible", subject to EU regulatory approval, the airlines had said.
Ryanair's chief legal and regulatory officer, Juliusz Komorek, said the airline welcomed the Commission's decision.
"Ryanair remains committed to bringing competition, choice and low fares to the Austrian, German and Spanish markets through our investment in LaudaMotion," he said.
Ryanair has also accused its German rival Lufthansa of bidding to undermine the new Austrian carrier.
The airline said Lufthansa wanted to remove nine of the craft that it was obliged by the Commission to deliver to LaudaMotion once it bought Air Berlin.
Ryanair said it was calling on the competition authorities to halt Lufthansa's "repeated abuses of its dominant position, which are designed to harm competition and consumers".
Lufthansa has refuted the Ryanair comments.