The 25-year-old joins on a three-year deal after the two clubs agreed a fee in the region of ?2.5million.
Proschwitz scored 17 goals in 33 appearances in Germany's second tier last term, but has clear designs on realising his top-flight ambitions at the KC Stadium.
"I'm delighted to have completed my move to the club," he told the Tigers' official website. "I think I have joined a great group of lads. Everyone is friendly, everyone is nice and, most importantly, everyone likes to work and train hard which is exactly what I like to do.
"I think Hull City is the perfect club for me and the next stage of my career - I'm proud to call myself a Hull City player. I had a great time at my previous club but that is in the past and the only thing I'm focused on now is my future with Hull City.
"Playing in the Premier League is a big goal for me and I believe Hull City can help me achieve that goal. I believe the Premier League and the German Bundesliga are the biggest leagues in world football and, if I can play in the top-flight of English football, it would be a dream come true for me."