Chiles had been set to compete in two events in the team final: vault and floor. After Biles withdrew, Chiles stepped in to compete on the balance beam and the uneven bars.
On Wednesday, Chiles shared what was going through her mind during an interview with Hoda Kotb and Savannah Guthrie on TODAY.
Chiles said she had to fill big shoes, but knew she could pull it off.
"I did it for a reason. I did it for her. She was with us the whole time," said Chiles, talking about Biles.
Biles, who is considered the greatest gymnast of all time, withdrew from the team final after a rocky vault performance. Biles first cited a medical injury as the reason for pulling out but later said the emotional toll of the Tokyo Olympics caused her exit.
"I really can’t say a lot because she has to tell her own story, but all I know is I’m going to support her no matter what... I will forever be by her side," Chiles said.
On Tuesday night, Biles announced she pulled out of the individual all-around competition, set for Thursday, to focus on her mental well-being. Phoenix, Arizona gymnast Jade Carey, who is headed to Oregon State University this fall, will take Bile's place in the competition, which starts at 3:50 a.m. on Thursday.
Carey initially did not qualify because she was the third-ranking American behind Biles and Sunisa Lee. International Gymnastics Federation rules limit countries to two athletes per event in the finals.
KGW spoke to Carey's soon-to-be coach at Oregon State University, Tanya Chaplin, who said Jade is known for the vault and floor events, not the individual all-around competition.
Chaplin said there's a chance she could medal in all three rounds. She's been texting and calling Jade over the last couple of weeks.
"You get as nervous as you do working with them day in and day out, you just want them to go out and be as successful as you know they are capable of," said Chaplin.
Team USA will compete in the Tokyo Olympics individual all-around final at 3:50 a.m. on Thursday.