"Maximilian was very keen to come here and test himself in English football," boss Tony Mowbray said.
"It's a challenge for him and his arrival will create additional competition for places."
Mowbray added: "He is a real competitor and comfortable with the ball.
Is Maximilian Haas the ideal replacement for David Wheater?
"The challenge for him is to acclimatise to the English game and then take any opportunity that comes his way."
The former Eintracht Freising centre-back arrives at the Riverside following the departure of former England Under-21 international defender David Wheater to Bolton Wanderers earlier this month.
Source: BBC Sport
Source: BBC Sport