Grinnage was signed by the Jacksonville Jaguars on August 14, 2017. He was waived on September 2, 2017, and was signed to the practice squad the next day.[3][4] He signed a reserve/future contract with the Jaguars on January 22, 2018.[5]
On September 1, 2018, Grinnage was waived by the Jaguars and was signed to the practice squad the next day. He was promoted to the active roster to replace injured tight end Austin Seferian-Jenkins.[6] Grinnage made his NFL debut and caught his first career pass, a seven-yard reception, on October 14, 2018, in a 40–7 loss to the Dallas Cowboys.[7] He was waived on November 12, 2018.[8]
The Spring League
Grinnage was selected by the Blues of The Spring League in their player selection draft on October 10, 2020.[9]