The state, to become the third to permit marijuana for medical use, will allow distribution of the drug at up to three dispensaries dubbed "compassion centers" by supporters, the Providence Journal reported.
In 2006, Rhode Island lawmakers legalized the drug for medical use, which allowed doctors to prescribe it to critically ill patients. But people had no legal way to buy marijuana.
Rep. Thomas C. Slater, who sponsored the House bill, is battling advanced cancer, the newspaper said.
"Sick people should not be forced to associate with drug dealers and the dark underbelly of society to get the help they need," he said.
Carcieri vetoed identical House and Senate bills June 12, saying legalizing the sale of medicinal marijuana would increase use for non-medical purposes and hurt children.
The governor also said dispensaries would make law enforcement officials' jobs more complicated and hinder anti-drug efforts.