The fire will be eight times the size of any ivory stockpile destroyed so far.
"Kenya plans to use the occasion to torch as many as 120 tonnes of ivory, the largest stockpile of ivory ever destroyed by any country, as proof of our commitment to zero tolerance for poaching and illegal ivory trade, " presidential spokesman Manoah Esipisu told reporters.
Kenya said "several" heads of state were expected to attend, along with Hollywood actors Leonardo DiCaprio and Nicole Kidman, and business tycoons George Soros, Paul Allen, Howard Buffet and Michael Bloomberg.
President Uhuru Kenyatta set fire in March 2015 to a giant pile of 15 tonnes of elephant ivory, which conservationists said then was the largest ever burned in Africa.
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Then, the pile of tusks burned made a dramatic three-metre (10-foot) tall pyre of tusks with huge flames, burning for several days until the ivory turned to ash.
The promised destruction of the remaining stockpile is now slated for April 29 and 30.
Veteran conservationist Richard Leakey, chairman of the government's Kenya Wildlife Service (KWS), has championed the destruction of seized ivory.
Leakey said the average weight of an elephant's pair of tusks was around 36 kilos, meaning the stockpile represents the death of around 4,000 animals.
But other conservationists put a tusk's weight to be now far lower, meaning the stockpile could represent the deaths of even double that number.
The campaign is being organized by billionaire Russian publisher Evgeny Lebedev, owner of Britain's Independent and Evening Standard newspapers.