Same sex couples now have similar rights to marriage and adoption in Jersey as straight couples.
Jersey's civil partnership law has come into force.
The idea was agreed in principle by the States in 2009, but it has taken three years for the law to be drafted and approved.
Steven Edwards, who has campaigned for greater equality, said: "People who've had civil partnerships in the UK are now legitimately recognised in Jersey."
He said this meant they could open a bank account, buy property, and have access to inheritance.
The civil partnership law will allow gay couples similar rights and responsibilities as a husband and wife.
It will allow them to adopt children and claim a joint pension.
More than 50 other Jersey laws had to be re-worded to give civil partners equal rights.