The service, held at Westminster Abbey, had a congregation of around 1,800, but face coverings were not mandatory after all legal restrictions were scrapped in England weeks ago.
Ms Sturgeon was seen sitting near Boris Johnson and other UK Cabinet ministers. Neither the First Minister, nor any other attendees nearby, were wearing a face covering.
Face coverings would have been mandatory in Scotland. This requirement is set to end for funeral and commemorative services on Monday, but will continue for another two weeks in shops and hospitality settings.
The Scottish Licensed Trade Association (SLTA) labelled Ms Sturgeon’s decision to delay the scrapping of face covering rules “particularly galling” in light of her not wearing a mask at the memorial service.
"While face coverings are not required south of the border as the rules changed at the end of January, surely it would have set an example for the First Minister still to wear hers at the Duke of Edinburgh’s memorial service given her decision to insist that in licensed hospitality, in shops, on public transport and some indoor settings in Scotland we are required to still wear them until April 18,” said managing director Colin Wilkinson.
Asked by Conservative MSP Murdo Fraser why she was not wearing a face covering at the ceremony, Ms Strugeon said: “I abided by the rules in place there”, adding that she wore a face covering on the train to and from London.