Sabalenka broke Rakhimova five times as she wrapped up victory in an hour to make a convincing start to her Roland Garros campaign.
Three-time Grand Slam champion Sabalenka will play Switzerland's Jil Teichmann or Italian qualifier Lucrezia Stefanini for a spot in the last 32.
The 27-year-old from Belarus has never reached the final in Paris, but the tournament appears more open than in recent years given the struggles of three-time defending champion Iga Swiatek.