It was the first time the six-time loyalist killer has set foot in the place since his failed attempt to kill Sinn Féin leaders Gerry Adams and Martin McGuinness.
Stone (67) enjoyed the sunshine as he and his DJ wife Karan watched members of the Orange Order mingle and chat to celebrate the centenary of Northern Ireland.
Later a parade watched by 100,000 supporters wound its way from Parliament Buildings to Belfast City Hall.
Stone and his wife were seated less than 100 yards from the huge statue of Sir Edward Carson - the founding father of unionism - sited half-way up the steep hill at Stormont.
The notorious loyalist looked relaxed as a he chatted with well-wishers and posed for 'selfie' snaps with passers-by, who consider him a loyalist folk hero.
And as this
Sunday World reporter approached him for a quick word, Stone smiled and said: "Ah, Mr Jordan... the man I love to hate!"
Yesterday, Stone revealed he had spent a third of his life behind bars. And recalling his previous trip to Stormont, Stone said: "It took me two hours to walk here to today. And the last time I was here, it took me two hours to get out of the place."
Stone chatted amiably about childhood friends on the Braniel estate and the health problems he endures on a daily basis.
"I have a long list. But what can I do?" he said.
On March 16 1988, Stone - who was still a relatively unknown figure - catapulted himself on to the world stage when he single-handedly launched a gun and grenade on an IRA funeral in the heart of republican west Belfast.
Stone killed three people and he injured another 60 before mourners caught up with him and tried to drown him in a swamp bordering Milltown Cemetery. Minutes later, armed RUC officers stopped a car which was taking Stone away from the scene at high speed.
The police fought hand-to-hand with an angry mob on the M1 motorway, before placing Stone under arrest and saving his life.
Stone was sent to jail for life, but was released in 2000 under the Good Friday Agreement.
Six years later, Stone was arrested again - this time in the revolving doors at Stormont as he tried to spring another terror attack on Sinn Féin chiefs Gerry Adams and Martin McGuinness.
The feared loyalist was armed with a knife and imitation pistol. But he also had a viable explosive device secreted on him when he was detained by security staff.
Stone and his wife Karan were two among tens of thousands of unionists who made their way to the grounds of Stormont yesterday to take in the Northern Ireland centenary celebration.
Earlier in the morning, Orange Order leaders welcomed members and guests to a special centenary breakfast at a nearby sports pavilion.
Orangemen from all over the United Kingdom, the Republic of Ireland and even as far away as Canada travelled to Belfast to take part in the celebrations.
Leading Unionist politicians Doug Beattie and Sir Jeffrey Donaldson enjoyed breakfast together and they were joined briefly by PSNI Chief Constable Simon Byrne.
As the crowds swelled around the main platform before the speeches, they were treated to some extremely skilful Lambeg drumming and a few pipes tunes.
Dressed in a stunning red, white and blue sparkly dress, singer Carla Wilson treated the appreciative crowd to a selection of British patriotic songs, including Land of Hope and Glory and Rule Britannia.
Grand Master Edward Stevenson - a veteran Orangeman from Fermanagh - welcomed distinguished guests, brethren, sisters and friends to the momentous occasion in east Belfast.
But it was left to the Reverend Mervyn Gibson, Grand Secretary of the Orange Order, to set the political tone for the day. And he flatly refused to countenance any moves towards a united Ireland.
"We have no interest in becoming an all-Ireland. Save your breath," he said.
"It doesn't matter what you promise or offer, it doesn't matter if every day was the 12th of July. If it's not under the Union Jack, then count us out!" he said to loud applause.
And to emphasise the point, he added: "British we are and British we'll stay!"
Rev Gibson accepted things had stalled politically as a result of unionist insecurity as a result of the Protocol.
He told the appreciative audience: "The immediate challenge that is hindering progress to achieve the vision shared is the Protocol. Not one unionist politician - not one - believes the Protocol is good for Northern Ireland!"
And in a snub to those politicians pressing for an immediate return to government at Stormont, he said: "The majority of unionists have voted that political unionism do not join an executive until the wrongs lurking in the Protocol are rooted out and thrown out."
More than 130 bands and around 30,000 marchers later took part in a huge Centenary Parade from Stormont to Belfast city centre.