Jac Holmes, from Bournemouth, Joe Akerman, from Halifax, and Irish citizen Joshua Molloy were detained by the Kurdistan Regional Government.
Mr Holmes posted on Facebook: "Got out of jail peeps, thanks for the support."
His mother met with Kurdistan officials on Friday to help secure his release.
The three men had been returning home at the time of their arrest, crossing from Syria into Iraq.
They were held for more than a week in a prison in Erbil.
Mr Ackerman updated his status on Facebook, simply posting: "Free".
"We are helping two British men make arrangements to leave Kurdistan after they were released from custody," a Foreign Office spokeswoman told the BBC.
Confirming the release of Mr Molloy, a former Royal Irish Regiment soldier, Ireland's Foreign Affairs Minister Charlie Flanagan said: "I welcome Joshua's release and I am pleased that he is now on his way home to join his family in Ireland."
We understand the men had been waiting on the border between Syria and Iraq for several weeks trying to cross. However, the border was closed.
They made their way to another point to cross and were arrested and told they were crossing into Iraq illegally.
The border is a politically sensitive zone between Iraq and Syria. The two countries have numerous groups in conflict with one another.
Jac Holmes's mother told me it had been an anxious time as the days passed, and that she had visited Kurdish officials in London to do what she could to get Jac and the other men released.
She wrote "I was prepared to chain myself to the railings" to try to ensure the men's safe passage home.
Kurdish supporters in the UK have rallied around in support Mr Holmes during his time fighting in Syria. He is one of a number of western volunteers fighting with the Kurds.
They call him a "hero", while British officials continue to warn strongly against travelling to any conflict zones.
The British Government maintains that anyone fighting abroad could find themselves breaching UK terrorism laws.

Shiralee Duncan, 37, was involved in a two-car collision at the A90 Charleston flyover at about 12:50 on Thursday.
The Dundee resident was taken to Aberdeen Royal Infirmary but died a short time later.
Police have appealed to anyone with information about the crash to contact them.

Sheffield City Council was ordered to stop felling trees in February after campaigners applied for a temporary injunction.
Mr Justice Gilbart lifted the order on Wednesday and is expected to hand down his final judgement next month.
The council said it would not implement its full felling scheme until the ruling.
Sheffield Tree Action Group (Stag) said it was disappointed by the news.
Executive director Simon Green said: "We are delighted that the court has agreed with the council's case to have the tree injunction lifted.
"However, we have been clear throughout that we want to make sure that our work with communities on this issue is right, so we will not resume the full street tree replacement programme until we have had the court's final decision.
"We will of course continue to assess our trees and replace those that are dangerous."
More than 3,300 trees have been removed across the city since 2012 as part of a Â£2bn project.
Campaigner Dave Dillner, from Stag, said he retained "a measure of confidence" over the High Court's final decision.
"It's absolutely not the end of the campaign. We wait with interest Mr Justice Gilbart's final judgement," he said.
The Labour-run council launched the scheme to remove dead and dangerous trees from the roadside.
It planned to remove and replace about 5,000 trees in total and has so far replanted about 3,600 trees.
Former Lib Dem leader Nick Clegg previously called on the council to abandon the programme and described it a "national scandal".
Three men arrested attempting to cross the Iraqi border after joining Kurdish forces to fight the so-called Islamic State group in Syria have been released, the BBC understands.
[NEXT_CONCEPT]
A woman who died from her injuries after a crash on the outskirts of Aberdeen has been named.
[NEXT_CONCEPT]
A ban on chopping down trees in Sheffield has been overturned by the High Court.