Nicola Sturgeon will attend the remembrance service for the 22 people who lost their lives in the bombing, including Barra schoolgirl Eilidh MacLeod.
The young piper, 14, was at the Ariana Grande concert with her friend Laura MacIntyre, 15, who was seriously injured in the blast.
Ms Sturgeon said: “Heading to Manchester today to pay tribute to those who lost their lives in the atrocity one year ago, including young Eilidh MacLeod from Barra.
“I hope today’s memorial service brings some comfort to the bereaved and to those who are still living with their injuries.”
Some of the hundreds of those injured in the explosion, and the families of those killed, will be attending the service at Manchester Cathedral this afternoon.
They will be joined by the Duke of Cambridge and Prime Minister Theresa May, as well as first responders to the scene, civic leaders and other national figures.
The invitation-only service, held between 2pm and 3pm, will incorporate a national silence at 2.30pm, which will also be marked at UK Government buildings.
Members of the public will be able to watch proceedings on a big screen in nearby Cathedral Gardens, while the service will also be screened at York Minster, Liverpool Metropolitan Cathedral and Glasgow Cathedral.