Mr Key then met Japanese Prime Minister Shinzo Abe in their first formal bilateral together.
Mr Key thanked Mr Abe for his contribution yesterday at the meeting of Trans Pacific Partnership leaders in Bali.
He said Mr Abe had added momentum to the process at a critical time.
Mr Key has secured a meeting with China's Premier, Li Keqiang, in Brunei tomorrow.
Mr Key told reporters Mr Li had requested the meeting.
The pair met in the Great Hall of the People in Beijing during Mr Key's official visit to China in April.
Mr Key met China's president, Xi Jinping, in Bali on Sunday, meaning Mr Key will have had two full bilaterals with both Chinese leaders in the course of a year.
Mr Li's meeting is expected to have a more economic focus.
Mr Key is staying at the opulent Empire Hotel and Country Club which was one of the failed ventures of the Sultan's brother Prince Jefri Bolkiah.
He will attend a gala dinner tonight though all events are confined to a convention centre. There are no engagements at the royal palace.