Shahzad Khan, 47, from Cardiff, repeated the ceremonial role he first performed at the official opening of the sixth Senedd in October last year, which was the Queen’s final trip to Wales.
Charles and the Queen Consort have travelled to Cardiff for the next leg of a home nations tour following the Queen’s death, after visits to Northern Ireland and Scotland.
They were at the Senedd on Friday for a motion of condolence from members of the Senedd, and also attended a service of reflection at Llandaff Cathedral and a reception at Cardiff Castle.
Mr Khan, who is a member of the Welsh Parliament’s security team, said: “I was very honoured to be the mace-bearer when the Queen visited the Senedd last year and I was lost for words when I was asked to do it again.
“I have a specific memory of the meeting – just looking at her as she entered the room was an amazing feeling and you could feel the whole room shift.
“I’ll keep that memory in my heart forever.
It will feel very different doing it as it’s a very sombre moment, but it’s also a privilege to be part of the transition to the reign of the new King
“Being the mace-bearer this time is in very sad circumstances, but myself and my family are proud of my role in this historic moment.
“It will feel very different doing it as it’s a very sombre moment, but it’s also a privilege to be part of the transition to the reign of the new King.”
During the visit to the Senedd, Charles and Camilla met members of the Welsh Youth Parliament and pupils from Ysgol Gymraeg Hamadryad in Butetown, Cardiff, who presented the Queen Consort with a posy.