The 23 year-old striker, who has scored 14 goals in League One this season, has signed a four-and-a-half year deal with the Terriers.
Town boss Mark Robins told the club website: "We have tracked the progress of Nahki for some time and we are delighted that we have secured his signature.
"At just 23 he has huge potential, which he has proven at Bradford in the last two seasons. He fits into our ethos of buying young, hungry players who have experience and that we can develop.
"His goalscoring record over the last 18 months is hugely impressive and we believe that he is ready to make the step up to the Championship.
"He will excite our fans and has already shown them what he can do with his goal in the Capital One Cup. I believe he will offer our frontline something different and I can't wait to watch him in action for Huddersfield Town.
"For a young man he has already achieved a lot in his career having reached the Capital One Cup Final and promotion with Bradford.
"His achievements and potential meant that he was coveted by a host of Premier League and Championship clubs and I am delighted that he has chosen to join us."
- Sports & Recreation
- Mark Robins