The roll call vote was conducted on the second day of the Democratic National Convention in Philadelphia, making Clinton the first presidential nominee for a major US political party. She will accept the nomination in a speech on Thursday.
At the end of the roll call, rival Sanders moved for a voice vote to unanimously nominate Hillary Clinton.
"I move that Hillary Clinton be selected as the nominee of the Democratic Party," he said.
Virginia Senator Tim Kaine will also be officially nominated to be the vice presidential candidate.
The convention brings a bitter primary race to a close. A number of Sanders supporters remained loyal to the Senator up until the very end, reinvigorated by the release of internal DNC emails that showed the ostensibly neutral organization had a systematic bias toward Clinton.