Michael Gove said the sale of ivory of any age, with limited exceptions, will be banned in an effort to reduce elephant poaching.
The move, which is still to be signed into law, comes after a consultation in which more than 60,000 people supported the introduction of a complete ban.
Campaigners say around 20,000 elephants are killed each year for their tusks.
Previous bans only applied to ivory produced after 1947. The new law is even tougher than the changes proposed in the October 2017 consultation.
Mr Gove added that the new law will "reaffirm the UK's global leadership on this critical issue, demonstrating our belief that the abhorrent ivory trade should become a thing of the past."
He said: "Ivory should never be seen as a commodity for financial gain or a status symbol."
Those breaking the ban by selling ivory will face a maximum penalty of five years in jail or an unlimited fine, said the Department for Environment, Food and Rural Affairs (Defra).
It added that the measure is tougher than rules in China and the US.
The US currently ban ivory apart from items older than 100 years, as well as items with up to 50% ivory.
The Chinese ban exempts "relics", with no specific date before which these must have been made.
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