The striker joined the Owls from Norwich after a successful loan spell.
The 28-year-old joined the Championship side after enjoying an excellent loan spell from Norwich City earlier in the campaign, and Loovens suggested that his permanent arrival is likely to benefit the club as they look to secure promotion to the Premier League.
"Gary is a quality striker and we are happy that he has signed a long-term deal here," he told the Star. "I played with him for over two and a half years at Celtic so I know him quite well.
"Gary is quite a timid guy but his job is scoring goals and that’s what he gets paid to do and he’s really good at it. That's why the chairman did everything he could to bring him back.
"He's a big part of the team so hopefully we can push on."
The former Scunthorpe man bounced back from a slow start to his time with Carlos Carvalhal's side to end his loan spell with six goals from 12 league appearances for the club, including four goals in his final two games before the loan came to an end.
And he picked up where he left off upon completing his permanent switch, scoring the opening goal in the draw with Reading last weekend.
His recent run of goals have helped put Wednesday in the division's top six, and Loovens is not only backing Hooper to continue his ruthless run in front of goal, but for his goals to also help the side in their efforts to remain in the promotion picture.