The company is offering $1.64 a share for the Irish airline’s outstanding shares, a premium of 38% over their prior trading price, the New York Times noted.
Ryanair already has a minority stake of 29.8% in Aer Lingus. It launched a failed bid to acquire the rival Irish carrier in 2006.
The Irish government retains a 25% stake in Aer Lingus, but will sell its interest in the airline as part of a deal with the International Monetary Fund.
The airline says that combining its operations with Aer Lingus would create “one strong Irish airline group” that would be more competitive with larger European airlines.
The deal faces possible problems from European regulators, who are currently examining Ryanair’s minority holding in Aer Lingus. Regulators shot down Ryanair’s last bid for Aer Lingus.
In response, Aer Lingus has asked its shareholders not to act on the bid.