On July 9, 2020, at about 1500 central daylight time, Envoy Airlines flight 3880, an Embraer 175, N226NN, encountered turbulence during descent into Chicago O’Hare International Airport (KORD), Chicago, Illinois. One flight attendant sustained serious injuries and one flight attendant sustained minor injuries. The airplane was not damaged. The regularly scheduled passenger flight was operating under the provisions of 14 Code of Federal Regulations Part 121 from El Paso International Airport (KELP), El Paso, Texas, to KORD. According to the flight crew, about 10 minutes prior to top of descent, they turned the seatbelt sign on after encountering a small pocket of light turbulence. Shortly after beginning the descent, the flight crew noticed cumulus clouds in the descent/approach path and the first officer (FO) called the flight attendants (FA) to notify them to expect turbulence during the descent. As the flight descended through about 15,000 feet and approaching several cumulus clouds, the FO again called the FAs and told them the flight would hit turbulence in about 60 seconds. Shortly after, when the flight was descending through about 12,500 feet, it encountered two sudden moderate turbulence “bumps”. According to the FAs, after being advised by the FO of the impending turbulence, FA 1 made a public address announcement to the passengers in preparation for landing. Both FAs were collecting trash and completing their compliance checks when the first turbulence hit the airplane, sending both FAs into the air and onto the floor. When the second turbulence event occurred a few seconds later, FA 2 was thrown almost to the ceiling and then onto an armrest, injuring her left arm. FA 2 had to remain on the cabin floor for the remainder of the flight due to her injuries. The flight crew declared an emergency and was given expedited vectors for landing. Paramedics met the airplane at the gate and FA 2 was transported to the hospital where she was diagnosed with a broken arm. FA 1 transported herself to the hospital after the flight and was examined and released with minor injuries.