With the arrival of Nikica Jelavic and Shane Long at the KC Stadium during the January transfer window and the likes of Danny Graham, Matty Fryatt and Yannick Sagbo also in the squad, first-team opportunities for the 27-year-old German have become limited.
Proschwitz arrived at the club in July 2012, but has only made five league starts in that time and none since Hull were promoted back to the Premier League at the end of last season.
He has scored twice in the domestic cup competitions for Steve Bruce's side, including a goal in his last appearance for the club against Middlesbrough at the start of January.
"Nick Proschwitz has joined Championship side Barnsley on loan for the remainder of the season," the club confirmed on their website.
"The loan deal for the striker runs until 3rd May and will give the 27-year-old German an opportunity to play regular first-team football as he looks to help Barnsley secure their Championship status."
Barnsley are bottom of the Championship after 25 games, with a Danny Wilson's side four points from safety after their victory over Blackpool last weekend.
