The German and assistant Christoph Buehler have put pen to paper on the new deals as part of the club’s planning for the new Championship season.
Wagner has already made five signings ahead of a campaign that Town hope to have 15,000 season ticket holders for after slashing adult prices to £179.
He said: “Christoph and I are both excited about the possibilities at Huddersfield. We are still realistic and humble about the Championship challenge but, on the other side, confident and ambitious enough to make the next steps on the journey we started six months ago.”
Town are anticipating bumper crowds next season and chairman Dean Hoyle believes the buzz created by the club’s first foreign head coach has played a major part in making the season ticket offer such an enticing one for supporters.
Hoyle added: “We have only just started the process of improving the club, but I sense the level of excitement among our fans is unparalleled since I became chairman. David – and Christoph – have played a huge role in that. That excitement carries to the people at the club, myself included.
“We are realistic in what we can achieve in the short term, but I am so happy that David and Christoph wasted no time in showing their commitment to what we want to do here in the long term.”
Another Yorkshire head coach in the Championship committing his immediate future is Barnsley’s Paul Heckingbottom.
The 38-year-old has signed a 12-month rolling contract after leading the Reds to promotion and success in the Johnstone’s Paint Trophy. Heckingbottom said: “We have to carry the momentum into the coming season.”