"Hillary Clinton must become the next president of the United States," Sanders told the crowd in Philadelphia.
His speech came after his supporters booed several of the first speakers of the evening, and he addressed that anger early in his speech.
"I understand that many people here in this convention hall and around the country are disappointed about the final results of the nominating process," Sanders said. "I think it’s fair to say that no one is more disappointed than I am.
"But to all of our supporters -– here and around the country -– I hope you take enormous pride in the historical accomplishments we have achieved."
Sanders was regularly interrupted by cheers of his name and spent three minutes taking in applause after taking the stage and before he started his address.
The drama on the floor won't necessarily end tonight, as Sanders himself hinted that it wasn't all about party unity.
“I look forward to your votes during the roll call tomorrow night,” he said, making it clear that he will not be releasing his delegates to Clinton.
He didn’t shy away from the gap between the two campaigns on issues, but sold the party platform reforms as a win for his supporters.
“It is no secret that Hillary Clinton and I disagree on a number of issues. That is what this campaign has been about. That’s what democracy is about,” Sanders said, to applause.
“But I am happy to tell you that at the Democratic Platform Committee there was a significant coming together between the two campaigns and we produced by far the most progressive platform in the history of the Democratic Party.”
He capped off his nearly 30-minute speech with one final shout out for Clinton.
"Hillary Clinton will make an outstanding president and I am proud to stand with her here tonight," he said.