During her illustrious career, she won 11 Olympic medals -- seven of them gold -- and 13 world championship titles.
"As a little girl they called chicken legs, never in my wildest dreams would I have imagined I'd have a career like this," Felix said in an Instagram post Wednesday.
"I have so much gratitude for this sport that has changed my life. I have given everything I have to running and for the first time I'm not sure if I have anything left to give."
The 36-year-old began her career specializing in the 200 meters, winning an Olympic silver at Athens 2004 and becoming the youngest ever world champion in the discipline in 2005 at age 19.
Her first Olympic success came at the 2008 Beijing Games when she guided the US women's 4x400m relay team to a gold medal.
This was the first of six relay Olympic gold medals -- four as part of the 4x400m relay and two in the 4x100m relay. Felix was also crowned the individual 200m champion in 2012.
"I want to say goodbye and thank you to the sport and people who have helped shape me the only way I know how -- with one last run. This season isn't about the time on the clock, it's simply about joy," her Instagram post continued.
Outside of athletics, Felix has highlighted the issue of maternal mortality among Black women, testifying before the House Committee on Ways and Means, after she gave birth to her daughter Camryn via emergency C-section at 32 weeks in November 2018.
In a New York Times op-ed, she accused her long-term sponsor Nike of penalizing her and other pregnant athletes in contract negotiations. She soon left Nike and signed with Athleta while Nike have since expanded their protections for pregnant women and new mothers.
Felix won two world championship gold medals less than a year after giving birth -- her 12th and 13th overall -- and surpassed Usain Bolt's record for the most world championship titles won by any track and field athlete.
"If you see me on the track this year I hope to share a moment, a memory and my appreciation with you," Felix said. "This season I'm running for women. I'm running for a better future for my daughter. I'm running for you."