The reform means people who have divorced and wish to remarry within the Church will find it easier.
The Catholic Church receives about 50,000 annulment requests every year.
Applicants have long complained it can take years to have a marriage declared null and void.
And costs can run into the hundreds, or even thousands, of dollars.
The Apostolic Exarch of the Greek Byzantine Catholic Church, Monsignor Dimitrios Salachas, says reforms are needed to stop people leaving the faith.
“Ninety per cent of weddings in our region are mixed — Catholic/Orthodox. People will not wait years and years for the two processes, they will just leave. We have lost the majority of Catholics due to the slowness of these processes.”
New laws introduced by Pope Francis simplify the process, eliminating mandatory reviews of annulment decisions and giving bishops power to judge clear-cut cases themselves.
The Pope wants simple cases completed in 45 days and fees waived.
Vatican analyst Josh McElwee says the reforms are extraordinary.
“I think it’s probably one of the most extensive reviews, most extensive changes to the Court of Canon law, which is the structure of law that governs the global Church, in centuries. The Pope basically removed the whole section of the canons regarding annulments, and put in new laws.”
The Catholic Church does not recognise divorce.
Those who remarry without a Church annulment are considered adulterers and are forbidden from receiving any of the Catholic sacraments such as communion.
Reuters Vatican correspondent Phil Pullella says, by making it easier for people to get annulments, the Church is showing mercy.
“It recognises that there are a number of people who have gotten married and didn’t have the prerequisites for getting married in the first place. That is, psychological immaturity, not total willingness, forced marriages, not realising fully — perhaps because people were very young when they got married — that marriage is forever.”
The reforms come a week after Pope Francis signalled a more merciful approach to women who had had abortions.
Australian pilgrim Sally Matthews was at Saint Peter’s Square in the Vatican when the details of the new annulment process were announced.
She says she welcomes the change.
“If they can simplify it to people that are in (an) unfortunate situation, where their marriage hasn’t worked and they have real reasons for the annulment … it’s not going to be as simple as saying ‘I want a divorce.'”
Pope Francis insists marriages remain an indissoluble union and says the new regulations are not meant to help to end them.