Democrats made history on Thursday, nominating Barack Obama as the first black presidential nominee of a major US political party.
A state by state roll-call vote was dramatically suspended when Hillary Clinton appeared on the floor of the Democratic convention and called for Mr Obama to be nominated by acclamation.
The motion was immediately put to the floor and carried.
Mr Obama defeated Mrs Clinton in a bruising race to become the Democratic nominee earlier this year.
Bill Clinton backs Obama
The former US president Bill Clinton has given a resounding endorsement to Mr Obama.
Mr Clinton told delegates that Mr Obama was uniquely qualified for the US presidency.
He described him as the embodiment of 21st century America with its ethnically culturally and diverse population.
Mr Clinton says he and wife Hillary will do everything possible to get Mr Obama elected.
"Everything I learned in my eight years as president and in the work I've done since, in America and across the globe, has convinced me that Barack Obama is the man for this job," Clinton told the crowd.
"Barack Obama is ready to lead America and restore American leadership in the world," he said, directly addressing the attacks on Obama by Republican presidential rival John McCain.
Clinton, one of the party's biggest stars, had been a loose cannon on the campaign trail during his wife's primary battle, frequently straying off message to level angry complaints about Obama.
On Wednesday, Hillary Clinton urged Democrats to unite behind Mr Obama, calling herself a "proud supporter" of the presidential candidate.
Mrs Clinton told the convention that it was time to unite as a single party with a single purpose.
The presidential vote will be held on 4 November.
see separate story in world news on John McCain's expected announcement this week of his Presidential running mate