Thomas Begley died and nine others, all Protestants, were killed when the bomb he was carrying exploded prematurely at Frizzell's fish shop on the Shankill Road on October 23, 1993.
Begley and a second bomber, Sean Kelly, wearing white coats and posing as delivery drivers, carried the bomb into the shop.
Begley (22) was later buried with full IRA honours in the republican plot in Milltown Cemetery, and his coffin was carried by former Sinn Fein president Gerry Adams. A year later Begley was commemorated by a parade through Ardoyne.
The 25th anniversary of his death will be marked at a Milltown commemoration tomorrow afternoon at 1pm.
Begley's elderly father, Billy, said the event has been organised by his son's comrades and friends. The family have previously publicly stated their opposition to the IRA bombing and their son's role in the attack.
Speaking at his home in north Belfast yesterday, Mr Begley said the family have been marking the anniversary privately this week.
"We have nothing to do with this event on Saturday and prefer to remember our son in our own private way. This week we have just been going to Mass and saying prayers for him. We also prayed for all the innocent people who were killed on that day," he said.
"We are very sorry for what happened - it was all wrong. Our family is not like that and if we had known what Thomas was going to do that day, we would have chained him to his bed."
Sinn Fein has confirmed that while tomorrow's commemoration has been organised by Begley's friends and not the party, some of its members will be represented at the event.
It will take place just four days after hundreds of people from both main traditions in Northern Ireland marked the 25th anniversary of the atrocity.
The mother of one teenager murdered in the bombing said the planned commemoration of her killer's death is "trampling on the graves" of all those who died.
One of the bomb victims was Gina Murray's daughter Leanne, who had celebrated her 13th birthday just four weeks before.
Mrs Murray (67) says this weekend's event to honour Begley is distressing for the families of the victims and will be hurting them all over again.
She said: "I'm not happy about this event at all - it only adds to the distress of this already very difficult week.
"Those behind it have no thought for this week's commemorations by the families of those who lost their lives.
"We were expecting something to take place on the actual anniversary of the bomb but at least they had the decency not to do anything then.
"They are always hurting us and now they are doing it all over again. We've had no break this week at all and this just tops it off.
"It's as though they are trampling on the graves of all those who were killed," she added.
Nationalist and unionist politicians were among those in attendance at Tuesday's anniversary service in West Kirk Presbyterian Church.
"The cross-community aspect of Tuesday's service was really wonderful and shows that people are trying to move on, but Sinn Fein are stopping them," Mrs Murray added.
Victims campaigner Willie Frazer has hit out at the planned commemoration for Begley, calling it "beyond grotesque".
He said: "Republicans call for equality and respect while they commemorate and glorify Provo terrorists, idolising and normalising actions of absolute depravity.
"Victims who speak out and condemn such commemorations are accused of living in the past, they're told to move on.
"Republicans need [to be] called out on their hypocrisy, their lack of respect and remorse needs [to be] highlighted and scrutinised."
North Belfast DUP MLA William Humphrey added: "Yet again Republicans seek to glorify a terrorist and terrorism. Let's be clear, there was nothing glorious or brave in what Thomas Begley did. Begley died planting the Shankill bomb, a device which murdered nine innocent people."