The 19-year-old will join the Pilgrims on loan until the January transfer window - subject to final National League, EFL and Football Association ratification.
The younger brother of Hull first team captain Lewie, Coyle junior is capable of playing in a variety of midfield roles.
Coyle has progressed through Hull's youth system and has been included on the bench in Championship action.
He has trained with the Pilgrims over the opening days of pre-season and becomes Graham Coughlan's 12th signing of the summer.