Addressing the second day of a two-day meeting, Biden said "a great deal of history of our world in the next 50 years is going to be written in the ASEAN countries, and our relationship with you is the future, in the coming years and decades".
The summit marks the first time that ASEAN leaders have gathered as a group in Washington and their first meeting hosted by a US president since 2016.
The Biden administration hopes the effort will show that Washington remains focused on the Indo-Pacific and the long-term challenge of China, which it views as its main competitor, despite the crisis in Ukraine.
"We're launching a new era - a new era - in US-ASEAN relations," Biden said on Friday.
Earlier, US Vice-President Kamala Harris told ASEAN leaders the United States would remain in the region for generations and stressed the need to maintain freedom of the seas, which Washington says is challenged by China.
"The United States and ASEAN have shared a vision for this region, and together we will guard against threats to international rules and norms," she said.
Neither she nor Biden mentioned China, which Washington accuses of using coercion against its neighbours, by name.
She said the United States would continue to respond with ASEAN to the threat of COVID-19, having already donated more than 115 million vaccines to the region.
She also said the United States and ASEAN needed to show collective ambition on climate change.
ASEAN includes Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam, though Myanmar's leader was excluded from the summit over a coup last year and the Philippines is in transition after an election and is represented by its foreign minister.
Biden opened the meeting on Thursday at the White House, and his administration promised $US150 million for infrastructure, security, pandemic preparedness and other projects.
However, US spending pales in comparison with that of China, which in November alone pledged $US1.5 billion in development assistance for ASEAN to fight COVID and fuel economic recovery, and US officials concede Washington needs to step up its game.
On Friday, Biden announced he was nominating a new ambassador to ASEAN, Yohannes Abraham, currently chief of staff on his National Security Council, to fill a post vacant since the start of the Trump administration in 2017.
ASEAN countries share many of Washington's concerns about Chinese assertiveness, including Beijing's claim of sovereignty over vast swathes of the South China Sea where Vietnam, the Philippines, Brunei and Malaysia have rival claims.
But they also remain cautious about siding more firmly with Washington, given their predominant economic ties with Beijing and limited US economic incentives.
