The Athletic reports Kerr is on the verge of a £500,000 move to the League One side with future additions which could see the fee rise.
The McDiarmid Park captain is in the final year of his contract alongside his fellow defensive partners Jamie McCart and Shaun Rooney, both of whom have attracted interest during the current window.
Kerr lifted the League Cup and Scottish Cup last season in a historic year for the Perth club as Callum Davidson’s men became only the second side outside of the Old Firm to capture both trophies in the same campaign. He was included in the SPFL Premiership Team of the Year for his efforts.
The 24-year-old has made 141 appearances for Saints since breaking through in the 2017-18 season following impressive loan spells at East Fife (twice) and Queen of the South.