Under the agreement, forces that had amassed on front lines in the country's north would pull back and Interior Ministry security forces will deploy to the centres of the cities of Hasakah and Qamishli in the northeast, both currently held by the SDF. Local security forces will be merged.
The sides announced the deal after Syrian government forces under President Ahmed al-Sharaa captured swathes of northern and eastern Syria from the SDF this month, forcing the Kurdish forces to retreat into a shrinking enclave.
The fate of the SDF, which once held a quarter or more of Syria, has been one of the biggest issues looming over the country since Islamist fighters led by Sharaa toppled President Bashar al-Assad 14 months ago.
The agreement includes the formation of a military division that will include three SDF brigades, in addition to the formation of a brigade for forces in the SDF-held town of Kobani, also known as Ain al-Arab, which will be affiliated to the governorate of Aleppo.
"The agreement aims to unify Syrian territory and achieve full integration in the region by strengthening co-operation between the concerned parties and unifying efforts to rebuild the country," according to the deal as announced by the SDF.
A senior Syrian government official told Reuters the deal was final and had been reached late on Thursday, and that implementation was to begin immediately.
US envoy Tom Barrack, who has been closely involved in mediation efforts, declared the agreement "a profound and historic milestone in Syria's journey toward national reconciliation, unity, and enduring stability".
Noah Bonsey, senior adviser with the International Crisis Group think-tank, said the deal was "a potentially historic turning point".
"It looks like both sides have succeeded in defining a middle ground that works for both of them on some incredibly difficult questions," he said.
"It spares northeast Syria what could have been a really ugly military showdown. Implementation will be tricky. There are a lot of challenges ahead," he said, adding that he was waiting to see all the terms.
The United States has been closely involved in efforts to mediate a deal between the sides for almost a year.
The SDF was once Washington's main Syrian ally, helping the US military fight Islamic State. But its position grew weaker as President Donald Trump built close ties with Sharaa.
