There also will be a $500-a-head reception and a $75 stand-up performance.
But don't expect a laugh a minute from Cosby, who in recent years has spoken forcefully and sometimes controversially about the need for black self-reliance.
"While I'm there on the 11th, I will be very happy to take pictures with people, greet them and say hello — and with a great deal of clenched-fist seriousness about the work that has to be done," Cosby told me in a telephone interview Wednesday.
The Cos agreed to do the event, and some door-to-door campaigning with Rolley at some point, after talking with Rolley by telephone recently.
Miller had arranged for Cosby to come to town twice, for a Park Heights block party in 2008 and for Black History Month in 2009, when she worked for then-Mayor Dixon.
"I really would like you to talk to this person," Miller recalled telling Cosby. "I think he's a rock star."
Cosby's reply, according to Miller: "What do you need me for if he's a rock star?"
"OK," she conceded, "he's not a rock star."
But Rolley is, she said, someone who shares Cosby's passion for "what's happening in urban cities and what's not happening."
Cosby agreed to give Rolley 20 minutes. They wound up talking for 40.
During that time, they talked about Rolley's master's degree in planning from the Massachusetts Institute of Technology and his poor childhood in Jersey City, N.J., where Rolley said he was physically and sexually abused.
"I do have a degree from MIT," Rolley recalled telling Cosby. "I also have a Ph.D. from the School of Hard Knocks."
Cosby was impressed.
"He spoke to me about his life and how he came up," Cosby said. "For the city of Baltimore, it just appears to me that this is a young man who, no matter what comes at him, he is not going to turn away from the people."
Cosby said he was basing his endorsement in large part on Miller's recommendation. Of course, Miller vouched for Dixon, too.
Dixon "sounded good and she showed at every function," Cosby said, calling her demise "rather sad."
The fundraiser will come at a critical time for Rolley, whose first campaign finance report is due Jan. 20.
"Word on the street is, 'Otis is good. He would be great, but there's no way he can raise money,' " Rolley said. "If I have a strong showing on the 20th, then that conversation will change."