The 24-year-old has moved to the John Smith’s Stadium for an undisclosed fee 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 today,” said Siewert, currently out in Austria at the club’s pre-season training camp.
“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 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.