The Boro-born striker is surplus to requirements at the London Stadium an now looks set to seal a dream move to his hometown club.
Hugill only joined West Ham from Preston in January for a fee of £9.5m, but he made just three cameo appearances in the Premier league during the remainder of the season.
At this moment in time it remains unclear if the move is a loan deal or a permanent transfer.
Boro are in need of fresh attacking options after seeing Adama Traore and Patrick Bamford leave the club of late, with Hugill set to offer fresh competition and a different approach up front.
Manager Tony Pulis recently professed his preference for having local players at the club and Hugill looks set to be the first benefit from that policy.
Hugill will become Middlesbrough's fourth signing of the summer, following in the footsteps of Aden Flint, Paddy McNair and Andy Lonergan.