Tens of thousands of civil have deserted the area since December 16, leaving its countryside "reportedly almost empty", Efe news quoted the UN as saying in a statement on Friday.
"Displacement during winter is further exacerbating the vulnerability of those affected," it added.
"Many who fled are in urgent need of humanitarian support, particularly shelter, food, health, non-food and winterization assistance."
There have been increased airstrikes in the region since mid-December, coupled with an advancement of Russian-backed forces on the ground.
At least 12 people, including four children and two women, were killed in recent aerial attacks and numerous others were injured, according to the UN.
"As a result of hostilities, tens of thousands of families fled their homes in an effort to reach safety," the UN statement said.
"Between 12 and 25 December, more than 235,000 people have been displaced in northwest Syria."
A volatile security situation along northern roads and fuel shortages in the south of the province have limited the movement of civil, the UN said.
Families seeking refuge in towns and cities have often found themselves in public buildings such as mosques, garages, wedding halls and schools, the UN said.
As a result of the increased attacks, many humanitarian organizations have also been forced to suspend operations in the area, the UN added.
The latest wave of displacement has compounded the ongoing emergency situation in northwest Syria that resulted in the displacement of an estimated 400,000 people between April and August.
Forces loyal to Syrian President Bashar al-Assad, with the support of close ally Russia, have stepped up operations in the rebel-controlled northwestern part of the country since the end of April.
During this time, more than 1,315 civil, including more than 335 children, have died, according to the Syrian Observatory for Human Rights.
( With inputs from IANS )