Women on the Isle of Man will soon be able to request an abortion within the first 14 weeks of pregnancy.
Tynwald President Steve Rodan said the Abortion Reform Act had received Royal Assent, meaning that the UK's Ministry of Justice has given its approval.
The Manx government is yet to announce when the new law, proposed by Ramsey MHK Alex Allinson, will be introduced.
Currently abortions can only be carried out after a rape or because of concerns about the mother's mental health.
Under the changes, Manx women will also be able to seek an abortion up to 24 weeks in cases of foetal anomalies of if there are serious social reasons.
Health Minister David Ashford MHK said: "We will now be working with clinicians to develop the service so that we can bring forward an appointed day order at the earliest practical opportunity and open a new chapter in our island's healthcare provision."
The Campaign for Abortion Law Modernisation (CALM) said the group was "delighted" by the "long overdue" change in the law.
"It's taken 24 years to update this cruel, discriminative law and decriminalise abortion and make abortion care part of reproductive healthcare," a spokeswoman added.
The changes were brought forward by Dr Allison in a private member's bill last year.
He said decriminalisation "changes abortion from being a criminal justice issue to a health matter, as it should be".
"This is the culmination of years of campaigning by numerous people across the island to improve our law and stop women having to cross the Irish Sea to access essential healthcare," he added.
'Dark and sad day'
Sue Richardson, of pro-life campaign group Humanity and Equality in Abortion Reform (HEAR), said it was a "dark and sad day for the Isle of Man".
"We will never stop fighting for the recognition of the humanity, dignity, and rights of every member of the Manx and human family," she added.
In Scotland, England and Wales abortion is legal up to 24 weeks, provided certain conditions are met, but not decriminalised entirely.
Northern Ireland only allows abortions in cases where the woman's life is at risk.
In a referendum last year, people in the Republic of Ireland overwhelmingly voted to overturn its ban on abortion.