"And we remember so that we remain ever-vigilant against the corrosive influence of hate in all its forms", he said.
The statement is a victory for Armenia and its extensive diaspora.
Despite decades of pressure from the U.S. Armenian community, successive presidents have skirted the genocide controversy due to worries about a rupture with North Atlantic Treaty Organisation ally Turkey, which has steadfastly rejected the assertion. "We do this not to cast blame but to ensure that what happened is never repeated". "It's certainly something that we are doing here in the United States", the official said.
"So for us on so many levels, the closest thing to that actually becoming official worldwide, it was when the United States and the president himself acknowledged the genocide".
"And we reaffirm with them our commitment to a world free of discrimination and persecution, where everyone can feel safe".
Erdogan, in a statement to the Armenian patriarch in Istanbul, said that debates "should be held by historians" and not "politicized by third parties".
"For millions of Armenians these wounds are still wide open".
Cavusoglu's foreign ministry struck a more strident tone.
Armenian Deputy Foreign Minister Avet Adonts, speaking at the memorial before Biden issued his proclamation, said a United States president using the term genocide would "serve as an example for the rest of the civilized world".
"With regards to the events of 1915, none of the conditions required for the use of the term "genocide" that is strictly defined in global law are met".
Armenia marks the day as the anniversary of the 1915 rounding up of some 250 Armenian intellectuals, regarded as the first step of the killings that eventually took an estimated 1.5 million lives. It says numerous victims were casualties of the war or murdered by Russians.
Moment Nasa reacts to successful Ingenuity flight
The Perseverance rover - which carried Ingenuity to Mars - watched the liftoff from a nearby overlook, filming as well. Ingenuity's goal on Mars was simply to show that rotorcraft technology can work in that kind of harsh environment.
Armenians on Saturday streamed to the hilltop complex memorializing the victims of massacres, deportations and forced marches under the rule of Ottoman Turkey.
He voiced hope for greater USA alignment against Turkish-backed Azerbaijan, which past year won back swathes of territory controlled by Armenia since a war in the 1990s.
Biden, whose call to Erdogan to inform him of the genocide recognition was their first conversation since the USA leader took office three months ago, signaled he hoped to contain the fallout.
Biden and Erdogan agreed in their call to meet in June on the sidelines of a North Atlantic Treaty Organisation summit in Brussels, officials said.
Israel's Yesh Atid party leader Yair Lapid praised the move, saying that it is "an important moral statement by President Biden".
The US Congress in 2019 voted overwhelmingly to recognise the Armenian genocide but the Trump administration made clear that the official US line had not changed.
Avet Adonts, Armenian Deputy Foreign Minister, speaking at the memorial before Mr Biden issued his statement, said an American president using the term genocide would "serve as an example for the rest of the civilised world".
"This principled stand represents a powerful setback to Turkey's century-long obstruction of justice for this crime, and its ongoing hostility and aggression against the Armenian people", he said.
"Turkey will raise a rhetorical fuss for a few days and perhaps delay acting on some routine requests from the USA military".
Ties between Ankara and Washington have been strained over issues ranging from Turkey's purchase of Russian S-400 air defense systems - over which it was the target of US sanctions - to policy differences in Syria, human rights and a court case targeting Turkey's majority state-owned Halkbank. In 2014, when he was vice president, Biden apologized to Erdogan after suggesting in a speech that Turkey helped facilitate the rise of the Islamic State group by allowing foreign fighters to cross Turkey's border with Syria.
Biden before taking office called Erdogan an autocrat and voiced support for Turkey's opposition.
The Biden administration has criticized Erdogan aides over homophobic statements - but has turned to Turkey for diplomatic efforts in seeking a peace agreement in Afghanistan.