Face masks will be required in public places in Marion County and when indoors with other people starting next week. Masks will also be required when outdoors and unable to social distance.
"I know many will not agree with this policy," Mayor Joe Hogsett said. "This is a major change to what normal means in Indianapolis."
Marion County will join the state in it's reopening phase 4.5 on July 9, the day when masks will start to be required. The city has lagged behind the state when it comes to reopening more businesses.
Indianapolis health officials says data has driven decisions concering opening. Marion County has seen a steady decrease in cases, hospital admissions and the number of deaths.
The county also reports the number of cases in younger people has grown steadily in recent weeks.
The county will differ from the state in not reopening youth overnight camps and continuing social distancing at religious services.
Marion County has seen the greatest number of COVID-19 cases in the state, with more than 11,000 so far.
Three other counties, Elkhart, LaGrange and St. Joseph, already require people wear masks in public spaces.