Mr Walsh was speaking after the Cabinet last night approved an offer for its 25% stake, on foot of new guarantees about Heathrow landing slots, connectivity and its future at Irish airports.
The Dáil is currently debating the bid and will vote on it tomorrow.
Opposition TDs and unions have hit out at the government for approving the takeover because of fears over jobs.
But Mr Walsh says Aer Lingus is 'vulnerable' and this takeover is the only way to secure employment at the airline.
“The best guarantee that anybody can have for job security is to be part of a successful, profitable airline” he said.
“Our offer for Aer Lingus will provide that cover, give it the ability to withstand the external pressures – in a way that would not be possible if Aer Lingus was to remain as a standalone organisation” he added.
