The three players cover all basis from defence through to midfield to up front as Westley looks to stamp his mark on the North End squad with some outgoings likely as well before the end of the window.
Chris Holroyd has signed on an 18 month contract from Rotheram. The striker came through the ranks at Crewe before featuring at Brighton last season in their promotion season.
Andy Proctor has signed from Accrington Stanley after picking up various awards at the East Lancashire club. Proctor has worked with Westley at Stevenage before.
Preston have also made a loan signing of Jamie McAllister at left back. The 33 year old will stay at the club until 18 February as Westley tries to solve Preston's problem position.