Ward arrives with plenty of Championship experience having helped both Norwich City and West Ham United achieve promotion to the Premier League.
The 28-year-old also played for Preston North End, Plymouth and, most recently, Nottingham Forest in the second tier.
Howe was pleased to add a player with Premier League and Championship experience to his squad ahead of the start of pre-season training.
He said: "We believe in Elliott as a player and a person. He ticks all the boxes for us, he is a really good athlete, he's excellent in both boxes and he's a real physical presence.
"Not only that but he is also technically an excellent footballer, which fits in with our philosophy and how we want to play out from the back and how we want our defence to be able to handle the ball.
"He is a leader as well, he's experienced and he knows the division, so for all those aspects I think he's a really important signing for us."