The marchers, including children in a well-known Camden drill team, walked several miles across the city to City Hall in 93-degree heat. Two marchers carried Skittles and iced tea to represent the items Martin bought before he encountered Zimmerman on Feb. 26, 2012.
Along the route, residents joined the march and cheered.
A 20-year-old Camden rapper known as Taz the Gifted said he stayed up until 3 a.m. Friday to write a song in Martin's memory that he performed.
Dubbed the Camden Awareness March Justice for Trayvon Martin, the gathering was intended to be part rally in opposition to the verdict and Florida's Stand Your Ground law, part healing, part reflection, and part remembrance.
A candlelight vigil for more than 100 victims of gun violence over the last 18 months was planned for Friday evening.
"We want to stop the violence in the city of Camden," said Gary Frazier, an activist and member of Camden Comeback, one of the community organizations behind the event. "At the end of the day, we're losing our children."
Cook said Martin's killing "causes us to look back on the individual lives we've lost here in the city. We have to come together to seek solutions for the situations that are plaguing our city."
In 2012, the city had 67 homicides, which brought it unwanted national attention. There have been 26 this year compared with 34 at this time last year.
Frazier is a City Council candidate; Cook is a mayoral candidate. But Frazier said the rally wasn't a political event.
Camden residents rallied on the same day that President Obama made his strongest and most personal statements about race in many years, and a day before 100 "Justice for Trayvon" vigils, organized by the National Action Network, are scheduled to take place nationwide.
"You know, when Trayvon Martin was first shot, I said this could have been my son," Obama said. "Another way of saying that is Trayvon Martin could have been me 35 years ago."
He said: "And when you think about why, in the African American community at least, there is a lot of pain around what happened here, I think it's important to recognize that the African American community is looking at this issue through a set of experiences and a history that, that doesn't go away."
Mayor Dana L. Redd said she, like others, was "still in disbelief," but echoed the sentiments of Obama and Martin's parents.
"We need to unify, and really delve into finding peaceful solutions to prevent senseless acts of gun violence that are plaguing our neighborhoods," Redd said.
Camden County NAACP president Colandus "Kelly" Francis joined the call of the national NAACP and civil-rights groups for the Justice Department to file civil-rights charges against Zimmerman.
Attorney General Eric Holder this week confirmed that the department will resume its investigation. City officials said Council would consider a resolution next month in support of a federal investigation.
Francis said the Stand Your Ground laws, which allow someone who believes he or she is in danger to use deadly force, were "another form of lynching," with a firearm rather than a rope. The police chief of Sanford cited the law as the reason for not initially arresting Zimmerman.
Tawanda Jones, cofounder of the Sophisticated Sisters drill team, said that at her house, "everybody just bursted out into tears" on the day of the verdict.
The team, which Jones and her husband founded in 1986, has drawn national attention with TV appearances. Members marched to City Hall and performed at the rally.
"A lot of the little kids are asking why," she said of the verdict.
Contact Darran Simon at 856-779-382 or firstname.lastname@example.org, or follow on Twitter @darransimon.