The 24-year-old has moved to the John Smith’s Stadium for a fee in the region of £250,000 after previously playing under Town head coach Jan Siewert in Germany for two years.
Bockhorn is primarily a right-back but he can also play on the left flank, and Huddersfield have an option to extend his stay by a further 12 months.
“It is great that we can welcome Herbert to Huddersfield Town,” said Siewert, from the club’s pre-season training camp in Austria.
“He has some very interesting qualities as a player. His versatility is a real asset. He can play at full-back on either side and on the wing, so he is a great player to have in our squad.
“The move to the Sky Bet Championship is a definite step up in quality for him but he is a player I know well, and I believe he will be a success here.”
Bockhorn’s arrival comes amid suggestions north of the border that Celtic are keen to push through a deal for Terriers right-back Tommy Smith. A fee of £3-4m has been suggested by sources close to the Glasgow club.
Town’s new addition – the fourth of the summer – was a regular in Dortmund’s second team under both Siewert and predecessor Daniel Farke.
He earned a call-up to the Ugandan international squad only for injury to deny him a possible debut.
Bockhorn’s only first-team appearance at Dortmund came in last summer’s International Champions Cup win over Liverpool.
Meanwhile, Town’s home game against Sheffield Wednesday has been put back a day to Sunday September 15 to be shown live on Sky Sports.
The Yorkshire derby, which will kick off at noon, is one of four matches involving clubs from the county to be selected in the latest round of matches.
Leeds United will host Derby County and West Bromwich Albion on Saturday September 21 (12.30pm) and Tuesday October 1 (7.45pm) respectively, while Barnsley’s home clash with Brentford has also been chosen for live broadcast on the satellite channel. The Oakwell meeting will now take place on Sunday September 29 at 1.30pm.