Stewart's car struck and killed Kevin Ward Jr at a dirt-track race in upstate New York on August 9.
Ontario County district attorney Michael Tantillo said he had reviewed the investigation and decided a grand jury should decide Stewart's fate.
"Upon my review of all of the information contained in the entire investigation, I have made the determination that it would be appropriate to submit the evidence to a grand jury, for their determination as to what action should be taken in this matter," he said in a statement.
"Accordingly, the evidence developed in the investigation will be presented to an Ontario County grand jury in the near future.
"As grand jury proceedings in New York State are strictly confidential by law, I am unable to state when the matter will be scheduled, other than to state that I intend to present the matter in the near future.
"Similarly, because of the confidential nature of these proceedings, I cannot state who will be called as witnesses, or what any witness's expected testimony will be.
"When the presentation has been completed and a determination has been made, I will advise the public and the media at that time of the results."
The three-time NASCAR Sprint Cup champion missed three races after the incident, but has been involved in the past three.
In a statement, Stewart said he would cooperate and looked forward to the end of the matter.
"I respect the time and effort spent by both the Ontario County District Attorney and the Sheriff's Office in investigating this tragic accident," he said.
"I look forward to this process being completed, and I will continue to provide my full cooperation."