Capacity will move to two-thirds from August 1, while stadiums will be able to function with no restrictions from August 16, said the decree published by Rio townhall on Friday.
The initial easing must allow for 4 sqm per person and ticket sales will only be online.
The Rio state championship has been the first to resume in South America, a region hit hard by the coronavirus pandemic.
The league, comprising professional teams within Rio state, resumed behind closed doors on June 18.
Brazil has the second-highest number of infections and deaths from the new coronavirus worldwide, after the United States: more than 1.2 million and 55,000, respectively.
And one of Brazil’s top football clubs, Fluminense, won its battle Friday not to play matches at a stadium also serving as a coronavirus hospital, which it argued was disrespectful to victims and their families.
Struggling to avoid the collapse of the health system as the pandemic surges in Brazil, authorities have set up a field hospital in the parking lot at Rio de Janeiro’s iconic Maracana stadium.
Paradoxically, the venue also began hosting matches again last week, after a three-month coronavirus hiatus on all professional football across the continent.