The striker makes the switch to The Showgrounds on an initial loan deal from Glentoran before a permanent three-year deal kicks in next season.
Mitchell made the switch to The Oval two years ago after successful spells with Dungannon Swifts and Glenavon.
The move to the Glens may not have worked out as Mitchell would have hoped but Kearney feels the striker "fits the bill" for what the Bannsiders are looking for and has shown the desire to make an impact on the Ballycastle Road.
"With the relation to the transfer market at the minute, you have to be smart and we believe that we have done good business by bringing Andrew to the club," he said.
"Andrew will join us on loan until the end of the season and then complete a permanent deal to join us in the summer on a three-year-deal.
"We believe that he fits the bill in the type of player we want to bring here as he's had a good career in the Irish League.
"It's fair to say that the move to Glentoran probably didn't work out like he wanted it to and he hit the pause button, but he's scored a lot of goals at this level and he has the want and desire to make up for lost time.
"He couldn't wait to the summer for the move to be completed as he's itching to get started and we look forward to working with him.
"We haven't had any issues creating chances this season but we probably haven't scored enough goals since December and Andrew can help in that department."
Mitchell will wear the number 22 shirt for the remainder of the season.