Tilley spent the first half of the season on loan at Yeovil Town in the Vanarama National League, making 21 appearances.
In the second half of last season the 21-year-old was with League of Ireland club Cork City, where he scored three goals and made three assists in 28 appearances.
He made his senior Albion debut in the Championship aged 16 in 2015, and made two more first-team appearances that season, scoring against Barnet in the EFL Cup at the Amex.
Under-23s coach Simon Rusk said, “James has been at the club a long time and he has always worked hard and been extremely professional for us.
“Hopefully he will progress at Grimsby. It’s a step up from Yeovil where he’s been playing, and we wish him well for the future.”
Transfer Blog January 2020
Stay across the transfer activity this January Brought to you by italk