At least two dozen people are set to start walking at 1 p.m. from police headquarters at the corner of Broadway and Seventh Street to City Hall in Frank Ogawa Plaza, said Roslyn Robinson, Daphne's great-aunt.
Concerned members of the public are invited to join the walk.
"We just want to keep her name in the public eye, we want to keep her face out there," said Robinson. "We don't want it to die down and we don't want to lose hope."
Today's event comes five weeks after 21-month-old Daphne was reported missing by her father, who told police she had vanished from his parked car on July 10 outside the Gazza Supermarket at 7838 International Blvd.
The father, 49-year-old Oakland resident John Anthony Webb, told police a stranger abducted his daughter from the car, where she had been sitting with her 87-year-old grandmother, who suffers from dementia.
Since Daphne's disappearance, her family has canvassed neighborhoods throughout Oakland and Alameda, knocking on doors and handing out fliers, Robinson said.
She said that so far, police have not relayed anything new, but that the family remains hopeful that someone has information about Daphne's whereabouts.
"We figure somebody has seen something, somebody knows something, even though they might not have seen the headlines when it first happened," Robinson said.
Representatives from KlaasKids Foundation, which was established in 1994 after the kidnapping and murder of 12-year-old Petaluma girl Polly Klaas, have also been helping with the search, she said.
"They're trying to do whatever they can to keep baby Daphne on the radar and gather public support to push law enforcement to solve this case," said KlaasKids founder Marc Klaas, Polly's father, who has helped counsel Daphne's family since her disappearance.
Klaas said that recently, Webb's disappearance has been eclipsed by the case of missing San Diego County teen Hannah Anderson, who was found safe in Idaho with her captor, James DiMaggio, on Saturday. Authorities believe DiMaggio murdered Anderson's mother and brother.
"I probably took 100 phone calls last week and only one of them was asking about baby Daphne," he said.
"This is still ongoing, nobody knows what happened to this child, and just as much as Hannah Anderson deserved to return home and be found, so does baby Daphne," Klaas said.
Daphne is described by police as black with short, curly black hair and a deformity in her left ear. She is 2 feet tall and weighs 30 pounds.
She was last seen wearing orange two-piece pajamas with pink hearts.
Anyone with information about Daphne's whereabouts is urged to call the Oakland Police Department's Missing Persons Unit at (510) 238-3352 or 911.