The sale will secure much-needed funds for KPMG with which to partially reimburse the fallen carrier's creditors. Reports have put the value of Monarch's Gatwick and Luton slots at £60 million ($115m).
It emerged last week that Monarch had £466m ($896.7m) of unsecured debt owed to passengers and businesses which was unlikely to be repaid. But former owners Greybull Capital and the Pension Protection Fund may get some of what they are owed out of Monarch's £164m ($315.5m) in secured debt, thanks in part to the sale of the Gatwick slots.
KPMG will also be able to sell Monarch's Luton airport slots after the Court of Appeal overturned a High Court decision which had stripped the fallen carrier of the right to sell the assets.
Other airlines had also been linked with the slots, including easyJet and Norwegian.
Blair Nimmo, partner at KPMG and joint administrator, said: "Our continuing focus is now on Monarch Airlines Limited's (MAL) Luton slots, as well as exploring potential rescue opportunities for MAL and its residual assets including its brand and associated licenses."
Monarch's collapse led to 1,858 workers being made redundant and the flights and holidays of about 860,000 people being cancelled. The repatriation by the Civil Aviation Authority cost £60m ($115m).
EasyJet and Norwegian declined to comment.