The brand enlisted local traders and a dive team to complete the stunt, who worked to position the partly submerged, oval-shaped creations on a floating barge located within the body of water.
Each egg measures roughly the height of a double-decker London bus, and weigh nine, six and four tonnes respectively.
The activity forms part of the brand's 'Bunny's been busy' campaign, which will see the Cadbury bunny hide eggs in unexpected locations across the country in the lead up to Easter.
The stunt is set to live on, with an exhibition that looks at how it was conceived and delivered planned to open within the nearby Loch Ness Visitor Centre.
The activity has also seen Cadbury donate £5k to the Loch Ness project, and £1k to the Royal National Lifeboat Institute to help support local services.
Agency PsLIVE is behind the Loch Ness stunt, meanwhile Golin, RPM, Fallon, Carat and Elvis are also working on Cadbury's broader Easter campaign.
Claudia Miceli, senior brand manager, Cadbury Easter said: "For many years Cadbury has been part of Easter in family homes and this year we wanted to mark the start of Easter season in a joyful and fun way.
"The Cadbury Easter Bunny will be hiding #EggsEverywhere this Easter season, so look out for more giant eggs popping up across the country."
Adrian Shine, Local Loch Ness expert and marine naturalist, who worked with Cadbury to install the eggs in the Loch added: "This is the first time we’ve had anything like this appear in the Loch and the result was very impressive – Nessie certainly has been given an Easter treat! It was great working with Cadbury on this and also having the opportunity to raise funds for our project."
The brand released initial details of its Easter campaign on Tuesday (1 March). It also recently teamed up with the London Contemporary Orchestra (LCO) to host a special music event inspired by each of its nine Dairy Milk flavours.