Her Royal Highness Princess Sirivannavari Nariratana Rajakanya was also at the Throne Hall to greet leaders and senior officials from countries around the world.
Significant figures from countries including China, the United States, Saudi Arabia, Japan, France, and Canada met with the royal family ahead of the last day of the summit, where delegates are seeking to forge an Asia-Pacific free trade area.
Earlier on Friday, police clashed with hundreds of protesters gathered near Democracy Monument about eight kilometres from the summit venue.
Police fired rubber bullets to prevent the demonstrators from marching to the venue and delivering their petition to protest Apec trade deals and call on PM Prayut Chan-o-cha to resign.
HM the King’s father, the late King Bhumibol Adulyadej the Great, hosted world leaders at the two previous Apec summits held in Thailand, in September 1992 and October 2003.