The Spaniard is currently in Glasgow ahead of signing for the Scottish giants where he will undergo a medical tomorrow morning.
Toral's time at Granada, which included just six appearances for the club, was ended after Arsenal activated a recall option in the deal which took him to Spain.
The 21-year-old shone in the Championship last season while on loan at Birmingham where he scored eight goals in 33 appearance, after impressing at Brentford prior to that.
A statement on Granada's website read: "Arsenal Football Club has decided to activate the option they had in the winter to recover Jon Toral, who maintained a link with the Granada CF assignment.
"In this way, the player ceases to belong to Granada from today and undertakes a new football challenge.
"Granada CF wants to wish the best of luck to a player who always defended with absolute professionalism our shield and that was the author of a beautiful goal against Osasuna in Copa del Rey this season."
Toral, who won goal of the season for a brilliant volley against Ipswich last year, sees his contract with the Gunners expiring this summer.