Relatives refuse to give up hope the girls will be found alive.
Those holding the vigil Tuesday night at Ellis Park began with prayers for the sisters.
"We love you, Diamond and Tionda," the girls' mother Tracey Bradley sang, along with the group.
In the summer 2001, police officers and volunteers searched the city for the two missing girls. Diamond Bradley was only three years old, and her big sister Tionda was just 10 years old.
Age enhanced photos show what the girls might look like now.
Since the two sisters went missing, relatives and supporters have held an annual vigil on the day of the disappearance. Tuesday's vigil was held under a tree as heavy rain fell just after prayers were said.
"We're in the rain, but we're not discouraged," said Rev. Paul Jakes. "Even though the storms of life come, we're encouraged to hold on."
"We're still searching and have hope for them returning back home," Tracey Bradley said.
The pleas for help had as much urgency Tuesday night as they did nine years ago.
"If there is anyone out there that knows anything about where Diamond and Tionda are, please call 911, call the police, call someone," Tracey Bradley said.
"Be involved because it could be your kids," said grandmother Mary Bradley. "I want this community to do what has to be done. People have moved. People have died, everything else. They know everything else. I'm sure somebody around here knows something."
"We miss you. We hope that you come home safe. That's all that we ask," said aunt April Jackson.
The girls' disappearance has been assigned to Chicago's cold case unit. Chicago police tell ABC7 there are no open leads, but they and the family hope attention to the anniversary will urge those who have information to finally come forward.