Warren called the Republican Party's presidential nominee a "selfish little sleaze ball" who "will never be president of the United States." She sought to convince millennial voters -- who have remained somewhat resistant to Clinton after her contentious primary fight with Sanders -- that his efforts to move the party left had been rewarded.
"I am proud of the debate that Bernie Sanders and Hillary Clinton had in our primary, way to go. I am proud that we are party that doesn't debate who has the smallest hands, or who can build the longest, tallest, fake gold-plated wall in the world. I'm proud that we are not looking for the most obscene way to demean women," Warren said.
The progressive firebrand also pointed to the 2016 Democratic platform, which included a series of policy compromises hammered out by the Sanders and Clinton camps ahead of the party's convention, as an example of what a unified party could achieve.
"Thanks to Bernie Sanders, we have the most progressive Democratic platform in American history," Warren said.
Warren also laced into Trump over recent allegations of sexual assault, all of which Trump has denied.
"You know, I want to say this -- that some people say it makes them sick to hear Donald Trump talk like that," Warren said. "Well not me. Donald Trump's words don't make me sick anymore. They make me furious."
At one point, Warren even clucked like a chicken as she mocked Trump's ongoing refusal to release his tax returns. "The big brave Donald Trump is too chicken to release his tax returns," she challenged.
CNN did not immediately receive a response from the Trump campaign to a request for comment on Warren and Sanders' remarks.
Flanked by Warren, Sanders also argued against Trump's candidacy by honing in on the Republican nominee's taxes.
"I have been running all over this country for a year and a half talking about a corrupt tax system. And in one day, Donald Trump did more to explain the corrupt tax system to the American people than I did in a year and a half. Thank you, Donald," Sanders said.
"What Donald said is, 'Yeah, I'm a multibillionaire. I've got mansions all over the world. But you know what? I, a billionaire, don't have to pay any taxes and I'm proud of it because you suckers are going to pay the taxes for me.'"
Warren has been an outspoken critic of Trump throughout his presidential bid, regularly attacking the Republican nominee in sharp terms. In the last month, she's called Trump a "nasty little bully" with a "dark and ugly soul" at various campaign stops.
Trump, for his part, has lived up to his reputation as a "counter-puncher" with regard to Warren, hitting back at her barbs with a few of his own -- frequently calling the Massachusetts senator "goofy" and "Pocahontas," a reference to her claim of Native American heritage.