The proposal, which if passed would have put pressure on the Executive to examine legislation surrounding marriage in the region, was opposed by the vast majority of Unionists.
Green Party leader Stephen Agnew, whose party jointly tabled the motion with Sinn Féin, said same sex couples were being denied fundamental rights under the current civil partnership laws.
The motion stressed that religious organisations would still be able to define and observe marriage as they saw fit, but said same sex couples should be allowed to have their unions recognised as marriage in the eyes of the state.
"That is why I am calling on all the other political parties in the Assembly to support my motion on equal marriage so that we send out a clear message that discrimination against any group in our society cannot and will not be tolerated," Mr Agnew commented.
Bronwyn McGahan, Sinn Féin equality spokesperson said she was extremely disappointed that the motion failed.
"Equality threatens no one and this motion today would only have given members of the LGBT community the same rights including legal rights as other married couples."
The motion also called directly on Stormont Finance Minister Sammy Wilson to introduce legislation to guarantee that couples of any sex or gender identity received equal benefits under the law.
But Mr Wilson said there was no widespread desire for change in the legislation surrounding same sex marriage in Northern Ireland.
"Can I at the very outset of this debate make clear my position as minister: I am opposed to gay marriage, I would have no intention of bringing forward any legislation to this House to facilitate gay marriage and I believe that in doing that I do reflect what is the general view in this society in Northern Ireland," he said
Ulster Unionist MLA Basil McCrea, who was one of three Unionists to vote in favour of the motion, said he did not understand why the DUP had made such a petition "on a matter that should have been a free vote".
Mr McCrea argued that marriage is not an "exclusively Christian concept" and has changed over the years.
By society accepting equal marriage, it does not mean everyone has to agree with the practice. Many Christians and followers of other religions may not 'agree' with every marriage that takes place.
The motion needed the majority of nationalist and unionist votes to pass, after the DUP lodged a Petition of Concern to the Assembly authorities - a process used for contentious issues.
It meant the motion was unlikely to pass, however if normal voting processes had taken place it still would have failed after the substantial Unionist 'no' vote.
TUV leader Jim Alistair said the motion represented the "perversion of marriage".
"This is not an issue of equality," he said.
"This is an issue of the perversion of marriage. Marriage historically for very good reason has been long defined as the union of one man and one woman and any society should be slow to tinker with and alter the bedrock of society which has served it so well."
But Alliance leader David Ford said his party supported the motion of civil marriage for same sex couples.
"At present civil partnerships are not equal to marriage," he said.
"However, Alliance Party policy on this issue is that there must be protection for churches and faith groups, and for clergy, that they would not be forced to carry out same sex marriage ceremonies or have ceremonies performed on their property. Today's motion was consistent with that position."
He argued that Article 9 of the European Convention on Human Rights gives protection for religious freedom which would prevent faith groups from being forced to carry out same sex marriages.
John O'Doherty, chair of the Equal Marriage NI campaign, said the LGBT community "have always had to fight harder and longer than our brothers and sisters in other jurisdictions to ensure our rights and we will not be disheartened by today's setback."
"We will continue to have this debate across Northern Ireland because we know that this is how we will change hearts and minds. We know that, as ever, there are many obstacles in our path to equality but we can only go forwards, never back.
"There is no doubt in my mind that equal marriage will become a reality in Northern Ireland," he added.