The popular Irishman, who became a real hero with Wednesdayites because of his never-say-die attitude was released in the summer by Chris Turner.
He will join up with Owen Morrison at The Hatters, another former Owl who did not achieve his full potential and then made a controversial cross-city switch to The Blades.
Geary is the ninth player to be snapped up by new employers after the mass cull by Turner. The others are Dean Smith (Port Vale), Brian Barry-Murphy (Bury), Jon Beswetherick (Bristol Rovers), Kevin Pressman (Leicester City), Mark Robins (Burton Albion), Paul McLaren (Rotherham United), Leigh Bromby and Alan Quinn (both Sheffield United).
So far, Terry Cooke has not been able to get a new club although he is currently training with Chesterfield, Haslam has had trials at Rochdale and Huddersfield, no news yet on veteran Robbie Mustoe while Chris Stringer has been forced to retire.
An Owls XI will take on Alfreton Town tonight at North Street, kick-off is 7pm while Turner is expected to play his strongest possible side against Birmingham City tomorrow night, that Hillsborough clash gets underway at 7.45pm.