Jersey's legal marriage age rises to 18 from today (24 March).
Previously, islanders could get married at 16 years old without parental consent.
The change now puts Jersey's law in line with the United Nations Convention on the Rights of the Child.
All couples will also now be able to have civil partnerships, regardless of sex, and married couples can covert to one.
Islanders getting married will now be able to choose a second wedding location as a backup when hosting an open-air wedding, in case of bad weather.
Another change in the island's laws is that the superintendent registrar can also refuse a child's name if it would cause confusion or embarrassment.
Superintendent Registrar, Claire Follain, said: "These are important amendments to the laws relating to marriage, civil partnership and birth registration which reflect a commitment to equality, human rights and the rights of children."
Minister for Home Affairs, Helen Miles said: "I'm pleased to see these changes coming into force . Not only are they important so that we comply with human rights legislation and protect the rights and welfare of children, but it is also what Islanders want.
"Prior to the laws being approved by the States Assembly in March 2022, public consultations were held in 2019 and Islanders clearly stated that they believe civil partnerships should be available to all couples. There was also a clear consensus among respondents that we should raise the age of marriage to 18 years old."
Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To Know.