The Bomber Command Memorial in Green Park was splashed in white paint between 7:45pm and 9pm on Sunday, according to police.
The RAF Benevolent Fund estimates the repair will cost around £2,000 and said it was the fourth time in six years the monument has been attacked.
The memorial commemorates 55,573 RAF Bomber Command personnel who died during the Second World War.
We are LIVE as work begins to remove vandalism to Bomber Command Memorial in central London. MORE: https://www.forces.net/services/raf/utterly-tragic-raf-bomber-command-war-memorial-vandalisedPosted by Forces News on Tuesday, 22 January 2019
The clean-up at the Bomber Command Memorial started early this morning.
A statue of Sir Winston Churchill on New Bond Street and the Royal Marines Memorial on The Mall were among other memorials that appeared to have been vandalised.
The Met said no arrests have been made, inquiries are ongoing, and that officers are "working to establish whether the incidents are linked".
CCTV footage from nearby the Bomber Command Memorial has been passed to police.