The 26-year-old centre-back joins for an undisclosed fee from National League rivals Gateshead.
Kerr has previously played in Scottish football with Motherwell and Cowdenbeath before he returned to English soil.
Hignett admitted he has secured this signature earlier than he thought he could do.
“We have a list of targets that we have been working on for next season,” Hignett told the club's website.
“Fraser was one of the names at the top of that list so I am delighted we’ve been able to do a deal to bring him in before the summer.
“He’s had an excellent season at Gateshead and played a lot of games so he was someone we were keen to bring here and we’re thrilled he’s decided to join us.”
Kerr could make his Pools debut this weekend when they head to Sutton United.