Prominent civil rights activist and member of Dr King's entourage Reverend Jesse Jackson, spoke to an emotional crowd from the Lorraine Motel balcony where Dr King was shot.
Commemorating 50 years since his assassination, Jackson said the "sore is still raw".
The famous reverend was there when the assassination took place and recalled the "pow!" of the gunshot that killed his movement's leader.
The hotel has since been transformed into the National Civil Rights Museum where dignitaries and members of the public gathered to listen.
"My friends, today, the hope is in the resurrection. As in the biblical case he is not-- he is gone. When you celebrate Barack winning campaign 2008 and 12, he is alive. When those children marched last week saying ban assault weapons, enough guns is enough, he's alive."
Former President Barack Obama also paid tribute via a video message, praising Dr King's vision and reflected on his legacy.
"We should take what victories we achieve, secure them, and then build on them," he said.
As the nation's first black president, Mr Obama stressed people should not become complacent, and to keep fighting for change.
"We can't be trapped or discouraged by what is. We've got to keep pushing for what ought to be."
