No group has taken responsibility for the attack. Police did not say what evidence they had that led to their charging the eight men.
Tanzanian President Jakaya Kikwete called the bombing, which injured at least 50 people during the opening of a Roman Catholic church Sunday, an "act of terrorism" and told the BBC the country stands ready to address the perpetrators.
"We are ready to deal with all criminals, including terrorists and their agents, who are based in the country or externally," Kikwete said.
The BBC said religious attacks are fairly rare in Tanzania, though there has been an increase in the last year. In neighboring Kenya and Somalia, al-Qaida-affiliated groups have sprung up in increasing numbers.