Parker, who was mayor during the 2010-11 quakes, is in a hospital care facility in Christchurch after suffering a heart attack, which was followed by a stroke late last year.
It was not clear whether he would attend the service but he has been spotted in the crowd and current mayor Lianne Dalziel will read a message from him during the service.
The service is being held at the Oi Manawa Canterbury Earthquake National Memorial and will be attended by the Governor General, Dame Patsy Reddy, and Prime Minister Jacinda Ardern.
The memorial service will begin at 12.30pm on Monday.
He was treated but then had a stroke on the morning of October 5, just days after he attended an event in Akaroa to mark the restoration of the historic lighthouse.
He collapsed at his Christchurch home with the life-threatening stroke causing an intracerebral haemorrhage (ICH), which is bleeding within the brain tissue.
