This is more than two-thirds of their original entry list of 389 athletes, despite the World Anti-Doping Agency (Wada) recommending a blanket ban after a doping scandal.
During a press conference on the eve of the Olympics, Russia's Olympic Committee president Alexander Zhukov said his country will have "the cleanest team" at the Games.
The Olympics opening ceremony takes place on Friday.
"The Russian team may have experienced the toughest checks of the Olympics, because they had to go through multiple tests and checked," said Zhukov.
"On top of all that, Russian athletes are going through additional testing which is taking place at the Olympic Village.
"So, as of now, the Russian team is probably the cleanest in Rio."
A three-person IOC panel ratified 18 shooters, 11 boxers, 11 judokas, eight tennis players, six sailors, five equestrian riders, three archers and one golfer, among others, on Thursday.
Russian news agency R-Sport said 29 swimmers and canoeing world champion Andrey Kraitor were also free to compete at the Games.
The International Weightlifting Federation excluded all eight Russians centered for Rio last week and the Court of Arbitration for Sport (Cas) ruled the ban had been "properly applied".
Appeals by 17 Russian rowers were also rejected at the hearing in Brazil.