Prince Harry and wife Meghan Markle, Duchess of Sussex, revealed their newborn son to the public on Wednesday, with the proud new mother declaring him 'a dream.'

The couple, known as the Duke and Duchess of Sussex, posed with their son for cameras at Windsor Castle — the first in a lifetime of photo calls for the two-day-old baby, who is seventh in line to the throne.

They did not reveal the name of the child, known for now as Baby Sussex.

Harry cradled the apparently sleeping baby, wrapped in a white blanket and wearing a matching cap, in his arms.

Prince Harry and Meghan, Duchess of Sussex, during a photocall with their newborn son, in St George's Hall at Windsor Castle, Windsor, south England on Wednesday May 8, 2019. (AP)

Meghan declared motherhood to be 'magic.' She said the baby had 'just been a dream.'

'He has the sweetest temperament. He's really calm,' she said.

Harry quipped: 'I wonder who he gets that from.'

Asked which parent the baby took after, Harry said it was too soon to tell.

'His looks are changing every single day, so who knows?'

The couple left the photo call to introduce the baby to his grandparents, Queen Elizabeth II and Prince Philip. The infant is seventh in line to the British throne and is the eighth great-grandchild of 93-year-old Elizabeth, Britain's longest reigning monarch.

The baby was born Monday at 5:26 a.m. (0426 GMT; 12:26 a.m. EDT) at an as-yet-undisclosed location.

Family members have welcomed the new arrival, with Prince William saying on Tuesday he was 'absolutely thrilled.'