Bell, who served on the City Council from 2000 to 2005 and was elected again to the council last fall, was hospitalized just days after the Nov. 6 election, according to family members and city officials.
Doctors performed at least two neurosurgeries to address Bell's severe sinus infection and induced a medical coma during treatment.
"It's a real tragedy. He was a young guy and he just got elected and never got a chance to serve that second term," said Councilman Tom Butt, who served on the council with Bell.
Prior to the illness, Bell was president and CEO of the Cooperative Center Federal Credit Union in Berkeley and had worked for 15 years as vice president and branch manager of a Bank of the West in Richmond, according to his 2012 campaign website.
During his time on the City Council, Bell oversaw major redevelopment projects including a $106 million grant that "demolished a 240-unit crime-plagued HUD public housing project and replaced it with 142 affordable housing units," according to a statement on his campaign website.
Councilman Jael Myrick was appointed in February to fill Bell's seat on the council.
Bell is survived by his wife, Shelley Ross-Bell, and two adult sons, Gary Bell Jr. and Germaine Bell.
Family members said Thursday morning that they plan to release a statement later in the day and have not yet made funeral arrangements.