Reyes Cleary is Barnsley's third signing of the summer.
The 21-year-old forward has signed a three-year deal with a further option in the club's favour.
Cleary was out of contract with West Bromwich Albion after coming through their academy and playing two first team games.
He was briefly loaned to League Two Walsall last season then National League Hartlepool for whom he scored six goals and added seven assists in 20 matches.
Sporting director Mladen Šormaz told the club website: “Reyes is a player we’ve been following closely. He fits what we’re looking for – young, hungry, technically capable and has the physicality required for the football we’ll play under Conor. He’s already shown what he can do at senior level, and we believe there is much more to come. This is a signing that excites us and reflects our continued focus on building a dynamic, progressive squad for the future.”
Head coach Conor Hourihane, added: “I’m thrilled to have Reyes on board. He’s got great attributes - pace, power, and a natural instinct in front of goal. He’s also versatile, which gives us different options across the front line. Most importantly, he’s shown a real desire to be here and be part of what we’re building at Barnsley.”