King sustained the injury while scrambling to his right on third down during Texas A&M's second series. The redshirt freshman left the field for evaluation and returned to the Aggies sideline in street clothes and on crutches with his foot in a boot.
Sophomore Zach Calzada replaced King at quarterback with the Aggies trailing 7-0.
King had 292 pass yards with two touchdowns and three interceptions, as well as 22 rushing yards, against Kent State in his first career start last week.
King, from Longview, Texas, was ranked by ESPN as the No. 3 dual-threat quarterback and No. 46 overall player in the 2020 recruiting class.