The 23-year-old, who made his international debut against Belarus in June, completed his move to David Wagner's side on Thursday.
Huddersfield have an option to make the right-back's move permanent at the end of the season.
"It was important in this window that we found a real competitor for the right-back position and in Florent, we have exactly the right player," said Wagner.
"Florent is one of the most exciting young right-backs in Germany and is a footballer who I believe will fit our system and style of play very well."
Wagner added: "He is a real terrier in defence and likes to attack whenever possible, which is perfect for how we want to play.
"I have met with him and he is a good character; he is eager to show he can play in the Premier League despite a lot of interest from some top clubs in Germany. I'm looking forward to working with him on the training pitch."
Huddersfield, who also signed attacking midfielder Abdelhamid Sabiri on Wednesday, are flying high after winning their first two Premier League games and host Southampton on Saturday.