The Dutchman was a free agent after leaving Celtic at the end of last season and therefore could sign for the Tigers outside the transfer window.
Hull chairman Paul Duffen claimed the club had beaten some "big clubs" in Europe to his signing.
"I'm delighted we have beaten off all the competition to bring him to the KC Stadium.
"We've definitely wanted an experienced, top-drawer striker who scores goals and Jan has scored prolifically in top leagues in Europe.
"It's what we need. We didn't score enough goals last season. Going forward we have a lot of new talent and Jan will play his part in using his experience to settle them down.
"'We've been looking at Jan since July and are really pleased we've turned his head.
"He's been looking at other big clubs in Europe but the Premier League is here he wants to come and play with us."