Initiative 105 qualified for the ballot Aug. 20 after the Colorado secretary of state's office verified petition signatures.
Measure proponents collected about 40,000 more signatures than the 86,105 that were required.
Under the proposal, any food that is genetically engineered or made with ingredients that were genetically engineered must be labeled as "Produced with Genetic Engineering."
Medications, animals fed or injected with genetically modified food or drugs, certain foods not packaged for retail sale and not intended for immediate human consumption, alcoholic beverages and animal feed are exempt.
The Colorado Department of Public Health and Environment would regulate the labeling.
Although most fruits and vegetables have been developed through traditional breeding techniques, most Hawaiian-grown papayas and a handful of squash and sweet corn hybrids are the products of genetic engineering.
If battles over similar proposals in California and Washington are any indication, Colorado's November election could be the most expensive in state history.
In the two Pacific states, large agricultural businesses and food and beverage companies contributed millions of dollars to help defeat GMO labeling initiatives.