The decision came after a petition drive by food blogger Vani Hari asking the company to stop using the chemical, azodiacarbonamide, as a dye in its bread, ABC News reported Wednesday.
Subway denied Hari's petition affected its decision, saying in a statement it was "already in the process" of removing the plastic-based chemical from their bread's ingredients.
"The complete conversion to have this product out of the bread will be done soon," the company said.
Hari began researching Subway's food ingredients in 2012. The chemical helps produce "the air within the foam of a yoga mat," she has claimed. "It does the same thing for bread."
The World Health Organization says azodiacarbonamide has been linked to respiratory issues and allergies. It is banned in Europe and Australia.
"I commend Subway for finally responding to me and now over 57,000 concerned citizens," Hari said. "Their swift action is a testament to what power petitions and individuals who sign them can have."
Hari has taken credit for Kraft Foods removing yellow dyes from the company's "Mac & Cheese" products for children.