General Sir Peter Cosgrove has been proclaimed governor-general during a ceremony at Parliament House in Canberra.

A 21-gun salute outside Parliament House has heralded the swearing-in of Peter Cosgrove as Australia’s 26th governor-general.

Wearing civilian attire and displaying a host of military and civil medals, General Cosgrove was sworn into the nation’s highest constitutional office by High Court chief justice Robert French.

Scores of politicians and dignitaries witnessed the ceremony inside the Senate chamber on Friday.

Earlier, Prime Minister Tony Abbott welcomed Sir Peter to Parliament House where he received a general salute from a military guard of honour.

He was escorted to the Senate by the Usher of the Black Rod and the Sergeant-at-Arms, passing by dozens of people gathered inside the main lobby.

The formal proclamation ceremony began with the reading of the Queen’s commission, the instrument by which a person is appointed governor-general “during our pleasure”.

Sir Peter, as required, made an oath affirming to be faithful and bear true allegiance to Queen Elizabeth, her heirs and successors.

As well he swore to do right to all manner of Australians “without fear or favour, affection or ill will”.

A proclamation of office was signed by Sir Peter and counter-signed by the prime minister.

Sir Peter said he was both humbled and proud to take office, not he was the 13th Australian to do so.

He paid tribute to his predecessor Dame Quentin Bryce and her husband Michael, saying they had given eminent service to the nation.

Australia prided itself on high levels of social inclusiveness, harmony and equity, he said.

“Compared to most nations on earth that pride is not misplaced.”

Yet, in the broad and some special sections of the community, Australia remained imperfect like a work in progress.

“There is a role for the governor-general … to reflect the community to itself without becoming partisan,” Sir Peter said.

“I will embrace those opportunities enthusiastically.”

The new governor-general and his wife Lynne were presented to government ministers, Leader of the Opposition Bill Shorten and Australian Greens leader Christine Milne.

The justices of the High Court and the heads of diplomatic missions also were presented to the vice-regal couple.

A reception is being held in the Members’ Hall to mark the occasion.