The King and Queen were welcomed by the Lord-Lieutenant of Co Antrim David McCorkell, mayor of Antrim and Newtownabbey Stephen Ross and North Belfast MP John Finucane (Sinn Fein).
They were serenaded by school children and took some time to chat with the youngsters before officially opening the gates to the Coronation Garden.
Garden designer Diarmuid Gavin accompanied Charles and Camilla, introducing them to those who have spent recent months working to realise his “whimsical” design, which includes music, moving plants and bubbles.
He said his team had been working around the clock in recent months to prepare the garden, and described his inspiration as “whimsy” to mark the coronation as well as engaging with people of all ages.
“They were wonderful – I got to spend a little bit of time with them, we went into the quiet garden with the water dancing and they were asking me where the plants came from, the idea behind the design, and they couldn’t have been nicer,” he said.
Charles and Camilla were told the special garden in honour of their coronation marks the beginning of a new green initiative for Antrim and Newtownabbey Borough Council.
The King smiled as Bring Me Sunshine played, while Camilla described the garden as not what she had expected, but complimented it as “absolutely lovely”.
Following the garden visit, the King and Queen went on to Hillsborough Castle in Co Down, the royal residence in Northern Ireland.
They met with pupils from a local primary school who have taken part in a competition to design coronation benches.
Northern Ireland Secretary Chris Heaton-Harris hosted a brief private audience with the King and Queen, before they attended a garden party and planted a tree within the grounds of the castle to mark the coronation.
DUP leader Sir Jeffrey Donaldson was among those in attendance at Hillsborough.
Sinn Fein vice president Michelle O’Neill did not attend the event.
However she said representatives from the party will be present at events during the two-day visit.
“Yes, I think there’s a whole raft of engagements and some of our MPs will be at local events in their constituencies,” she told reporters after a meeting with the secretary of state at Hillsborough castle earlier on Wednesday.