McCarthy will take over from current Breyer finance director Neil Fisher who is retiring.
She spent seven years at Readie Construction before the business went into administration last month.
McCarthy said: “I am delighted to be appointed FD for Breyer and look forward to building upon the solid foundation and legacy that Neil leaves behind.
“Breyer’s values of placing people at the heart of what they do, improving the lives and communities in which they work, was key to my decision to taking this position. The business has a solid reputation within the sector and I will be using my experience of digital transformation to add further value to Breyer and its clients.”
Daren Moseley, managing director of Breyer, added: “We’re really pleased to have Jess on board. She is a great fit for the Breyer business, bringing immense experience of financial and systems management within the construction and property services sector.
“We are also delighted that Neil will remain with Breyer for the foreseeable future, working on specific projects and continuing to facilitate a seamless handover to Jess.”