The Irish 25-year-old signed his first professional deal when joining Sligo Rovers where he saw action in Europa Conference League Qualification games.
He established himself as their number one before Wrexham signed him on a loan in August 2023 with an option to buy in January, which they triggered.
At the start of last season McNicholas signed on loan at Rochdale, managing to hold Rovers to a goalless draw before returning to Wrexham due to injury in February.
A calm presence between the sticks who likes to use his feet and command his area with his height.