US President Joe Biden was among the first to confirm he will be at the event, which will be attended by up to 2,000 people.
“I don’t know what the details are yet but I will be going,” Biden told reporters on Friday.
Brazil’s Jair Bolsonaro and South Korea’s Yoon Suk Yeol are among the presidents attending the Queen’s final send-off following a series of ceremonial events.
The UK’s newly elected Prime Minister, Liz Truss, will also mourn the monarch next week.
“I would prioritize of course, alongside the Governor-General, doing our duty in representing New Zealand and to pass on the condolences of our whole nation,” Ardern told TVNZ Friday. “I do expect there will be a number of leaders looking to pay respects and tribute to the Queen,” she added.
Japanese Emperor Naruhito and Empress Masako will travel to London for the Queen’s funeral, an unusual move that demonstrates the close relationship between the Japanese and British royal families.
Japanese news outlet Asahi Shimbun reported, citing Imperial Household Agency officials, that a Japanese emperor has only attended the funeral of a foreign head of state or royal family member on one previous occasion, when then-Emperor Akihito attended the funeral of Belgian King Baudouin in 1993.
Members of foreign royal families will also be seated in the pews on Monday.
Spain’s King Felipe VI and his wife Queen Letizia are among the European royals who will attend.
The King and Queen of the Netherlands, together with the country’s former Queen, Beatrix, who abdicated in 2013, will also be in the congregation, the Dutch royal house announced.
Not all world leaders have been invited, however.
Representatives from North Korea and Nicaragua have been invited “only at ambassadorial level,” PA added.
The leaders of Russia, Belarus and Myanmar will also be absent.
Although Russian President Vladimir Putin did tweet his congratulations on King Charles III’s ascension to the throne, diplomatic relations between the UK and Russia have all but collapsed since Russia’s invasion of Ukraine, a senior UK government source told CNN on Tuesday.
Myanmar will not be invited, following a coup in the country last year.
After the funeral, Queen Elizabeth II will be buried at St. George’s Chapel in Windsor Castle, where her parents, her sister, Princess Margaret, and her husband, Prince Philip, are also buried.
CNN’s Alex Hardie contributed to this report.