The four-day convention is being held virtually in view of the coronavirus that has so far killed over 170,000 people and infected 5.4 million in the US.
The convention would formally nominate Biden, 77, as the party's presidential candidate and Indian-origin Senator Kamala Harris, 55, as his running mate.
Harris, the first-ever black and first-ever American of Indian and African descent to be nominated as a vice presidential candidate by a major political party, made a few brief appearances during the first night as part of the former presidential candidates' address.
Harris was a presidential aspirant until last year before she dropped out of the race because of lack of popular support.
We all ran for president motivated by the same reasons, said Harris who is scheduled to address the convention on Wednesday.
"Donald Trump does not understand who we are as Americans. He really doesn't, she said in another brief remarks as speakers after speakers at the convention slammed the president for his policies, which they alleged has divided the country.
If Trump is reelected, "all the progress we have made will be in jeopardy", former presidential candidate Senator Bernie Sanders said as he accused the president of being negligent to the pandemic which has resulted in job losses of 30 million people.
According to Senator Cory Booker, who was also a presidential aspirant, "We've got one shot to make Donald Trump a one-term president, and that shot is right now."
Another former presidential candidate Senator Amy Klobuchar alleged that Trump is trying to divide people and is also not responding to the coronavirus pandemic and the significant needs of the US economy.
Indian-origin Democratic politician Sara Gideo, who is running for US Senate seat from Maine, said with Biden in the White House and a Democratic Senate, the US can build back its economy and its communities even stronger.
In a major embrassment to the Republican party, former GOP (Grand Old Party) governor John Kasich, who participated in the event, said America is at a crossroads.
"Sometimes elections represent a real choice, a choice we make as individuals and as a nation, about which path we want to take when we come to challenging times. America is at that crossroads today," the former Ohio governor said.
"The stakes in this election are greater than any in modern times. Many of us have been deeply concerned about the current path we've been following for the past four years. It's a path that led to division, dysfunction, irresponsibility, and growing vitriol between our citizens," Kasich said.
Several speakers shared their vision of a future where US leaders look out for the middle class and bring access to affordable health care, housing and education within the reach for hardworking families.
Greg Weaver, a former Amtrak conductor and friend of Biden, said how the presidential candidate cares about ordinary, hard-working Americans and how he treats them with dignity and respect.
Congressman Cedric Richmond of Louisiana reflected on how America's small businesses make "our neighbourhoods feel like home, and reframed the conversation around the nation's economic challenges in a way that puts working people first".
New York Governor Andrew Cuomo in his remarks alleged that Trump's actions left America vulnerable and divided during a global pandemic.
One of the last things that my father said to me was that he felt betrayed by the likes of Donald Trump. And so, when I cast my vote for Joe Biden, I will do it for my dad, Kristin Urquiza from Phoenix, Arizona, said sharing her story.
Megan Rapinoe, star of the US Women's soccer team, led a conversation with medics on the frontlines of the pandemic about how their colleagues are risking their lives every day in harrowing conditions, making unimaginable sacrifices, and lacking the most basic equipment to do their jobs: saving the American people.
Biden also made a few brief appearances during the virtual convention. In one of those segments he engaged with and listened to social justice activist Jamira Burley, Chicago Mayor Lori Lightfoot, Houston Police Chief Art Acevedo, NAACP president Derrick Johnson and author Gwen Carr, and discussed how Americans can embark together on the path forward toward true equality, fairness, and justice for all.