The US has called an agreement between the Ethiopian government and rebel Tigray forces to cease hostilities a "momentous step".
The agreement was announced by an African Union envoy following peace talks in South Africa.
"We welcome the momentous step taken in Pretoria today to advance the African Union's campaign to 'silence the guns'," he said on Wednesday.
"We welcome the unimpeded delivery of humanitarian assistance and the protection of civilians that should result from implementation of this agreement."
Mr Blinken praised the "extraordinary efforts" of African Union mediators including Nigeria's former president Olusegun Obasanjo, Kenya's former president Uhuru Kenyatta and South Africa, the host of the talks that involved US envoy Mike Hammer.
UN spokesman Stephane Dujarric said the agreement was "very much a welcome first step, which we hope can start to bring some solace to the millions of Ethiopian civilians that have really suffered during this conflict".
Ethiopian Prime Minister Abiy Ahmed sent troops into Tigray in 2020 after accusing the Tigray People's Liberation Front — a group that spent decades at the centre of Ethiopian politics — of attacking federal army camps.
Since then, the fighting in Africa's second most populous country has forced more than two million people from their homes.
Researchers estimate that at least 600,000 people have died in Tigray, either as a direct result of the fighting or from related issues such as famine or the healthcare crisis caused by the Ethiopian government's blockade of the northern region.
The EU called for the launch of broader political talks and accountability for the victims of the fighting to ensure a lasting peace.
"It remains of the utmost importance that the victims see justice being brought upon the perpetrators of those crimes," EU foreign policy chief Josep Borrell said. "Accountability is a cornerstone for lasting peace and reconciliation."
The two-year conflict has severely soured relations between the US and its historic ally Ethiopia, with President Joe Biden's administration removing the East African nation from a major trade pact, citing human rights concerns.
While stopping short of promising a return of Ethiopia to the African Growth and Opportunity Act, US State Department spokesman Ned Price said of the agreement with the rebels, "It does present an opportunity, a bilateral opportunity, for the United States and Ethiopia."
Mr Blinken welcomed a statement by Mr Abiy, who promised to implement the accord.
He said the US shared "his desire for an enhanced partnership to support reconstruction and development for all communities in northern Ethiopia affected by the conflict".