While Harper is expected to start behind Allan McGregor in the Tigers' pecking order, Bruce expects the experienced stopper will bring wider benefits to his squad.
"Steve's experience will be a great help for us and I'm delighted to welcome him on board," said Bruce.
"He's had virtually 20 years in the Premier League so he's vastly experienced.
"Steve will come in and help the younger lads in the squad because he's a great pro and a good lad around the dressing room.
"It's vitally important to have that and we've now got three goalkeepers that are all ours."