Police said they received a report of criminal damage at the hall in the Main Street area of the town at around 9.30am on Thursday.
Sectarian graffiti was sprayed on the walls of the building.
The Grand Orange Lodge of Ireland has condemned the overnight attack, which it says is the 18th involving one of their halls so far this year.
Glenavy District Secretary Tommy Ross said: "This is a despicable hate crime which bears all the hallmarks of a deliberate sectarian attack.
"It is all the more abhorrent given that the local lodge held its regular monthly meeting in the hall last night. Yet, only hours later, faceless cowards - under the cover of darkness - ran amok and engaged in such obscene activity."
He added: "Those responsible should be ashamed of their actions, which are not reflective of the excellent neighbourly relations in Crumlin.
"We hope the community will unite in its condemnation of this attack."
They will not be allowed to damage the excellent community relations that exist within the town.
Anne Marie Logue
Sinn Féin councillor for Crumlin, Anne Marie Logue, also condemned the incident, she said: "This was wrong and in no way can be justified.
"Those behind this sectarian attack are not representative of this community nor are they - despite scrawling IRA on the hall several times - in any way republican.
"Only last week hundreds of people from across the community enjoyed the Christmas tree lights switch on.
"That is what Crumlin is about and a few mindless individuals will not stop this."
Police have appealed for anyone with information to contact them.