NI Secretary James Brokenshire and Irish Foreign Minister Charlie Flanagan will sign the treaty in Dublin later.
The Independent Reporting Commission proposed the body as part of a way to end last year's political impasse at Stormont.
The talks will also include issues arising from the Brexit vote.
Speaking ahead of Tuesday's meeting, Mr Brokenshire said: "There was never any justification for paramilitary groups, there is none today and there will not be in the future.
"The IRC provides for an independent review of progress towards disbanding paramilitary groups which continue to blight our society.
"For generations, paramilitary activity wrecked lives in Northern Ireland, and for many people the repercussions continue."
The IRC's annual reports will be published by the two governments.
The commission may make recommendations to the Northern Ireland Executive to inform future Programme for Government priorities and commitments.
The IRC will have four members, with the British and Irish governments nominating one member each and the Northern Ireland Executive two members.
Mr Flanagan said it was "another landmark day for Northern Ireland".
"This is an important step in implementing the Fresh Start Agreement provisions to eliminate paramilitarism and tackle organised crime," he said.
He said he would hold talks with Mr Brokenshire on the still stalled efforts to establish new mechanisms to deal with the legacy of the Troubles in Northern Ireland.
"As co-guarantors of the Good Friday Agreement, it is vital that the Irish and British governments continue to work together in a spirit of partnership to deliver on the full promise of that agreement and subsequent agreements," he said.
"Of course, we will also be continuing our discussions on the implications for Northern Ireland of a UK-exit from the EU."
The Irish and British governments are to sign a treaty establishing a body to work towards the end of paramilitary activity in Northern Ireland.