The event was held at Temple University's Liacouras Center.
Families, long-time voters, and college students who will get the chance to vote in their first presidential election were in attendance.
The night was filled with music and strong messages.
"America is ready to turn the page. America is ready for a better start. We are ready for President Kamala Harris," Obama told the crowd.
Action News spoke with some of the rally's attendees about what issues are most important to them.
"I would say issues regarding gun control and abortion," said Temple student Jezrael Obale.
"I think women's rights, the right to choose, that is so critical," added Jordyn Panzer from Gladwyne.
"Gun violence. It's really scary to see some people are not making it past 18, barely 15 (years old), in Philly," noted Temple student Amber Greene.
Harris wasn't at the rally herself, as she was in another battleground state: Michigan. There, she tried to fire up college-age supporters and draw contrasts between herself and her opponent.
"Cause my opponent spends full time talking about, just kind of diminishing who we are as Americans, and talking down, and talking about that we're the garbage can of the world. We are not," she said.
The vice president and Democratic presidential nominee was in Philadelphia on Sunday.
She made stops across town, saying the path to the White House runs through Philadelphia.
Harris said that "no one can sit on the sidelines" in this year's presidential election as she continued her focus on this battleground state.
Actions News anchor Walter Perez spoke exclusively with Harris inside West Philadelphia's Philly Cutz barbershop, where she discussed her priorities for her first 100 days -- if elected.
Kamala Harris discusses latest polls ahead of Election Day in Action News interview
"The highest priority is bringing down the everyday costs -- prices of groceries still too high," she told Perez.
Meanwhile, former President Donald Trump spent the day in Georgia on Monday speaking at a faith-focused event. He said he believes religion is under threat in the U.S.
"God wants our country to be helped. It would be a really nice thing to say that but now we need to win an election too," Trump said.
Trump also hosted a rally at Madison Square Garden on Sunday, where supporters filled the 19,000-seat arena.
Elon Musk, Hulk Hogan, and Robert Kennedy Jr. were among the big names in attendance.
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"Kamala, you're fired! Get out get out. You're out," Trump said to the crowd.
He spoke repeatedly about immigration, improving the economy, and providing tax cuts and credits.
"With your vote in this election, I will end inflation. I will stop the invasion of criminals coming into our country, and I will bring back the American dream," he said.
Trump will be back in the Philadelphia area on Tuesday as he makes appearances in Allentown and Drexel Hill.