New parents in Jersey will be able to claim up to 32 weeks of parental allowance from the start of next year.
The new measures will mean either parent can claim the allowance, including adoptive and surrogate parents, from 1 January.
Under the current law, only a mother can claim an allowance of about £225 a week, and only for up to 18 weeks.
The Children's Commissioner said the extension of the scheme was "brilliant news for our children and families".
The final reading of the new proposals was approved by 40 votes to one, with eight members absent.
The weekly value of the allowance will remain the same, meaning new parents will be able to claim up to £7,200.
'Support more parents'
A temporary scheme was launched in June to help businesses pay for parental leave in the interim.
The government offers businesses up to £1,335 per parent to help pay a second partner while the benefit laws are updated, and is therefore available until the end of 2020.
Minister for Social Security, Deputy Judy Martin, said: "We recognise that families look very different in 2020 than they did in the mid-1970s, when we originally introduced the Maternity Allowance and Maternity Grant.
"The introduction of parental benefits means that we can support more parents to have as much time as possible with their children during those crucial early years,"