Lufthansa had confirmed it will sell budget carrier bmibaby to an unnamed company in the UK.
The move comes ahead of a proposed £172.5 million sale of parent bmi to British Airways.
Lufthansa did not disclose the terms of the deal.
However, the buyer will assume all assets and liabilities of bmibaby, including aircraft and the current route network.
bmi expects the transaction to be signed in the first quarter of 2012.
The bmibaby route network will remain unchanged for summer 2012, with the new owners also entitled to use the brand for an interim period.
bmibaby will continue to operate basses at East Midlands, Birmingham and Belfast City airports.