Lancashire Care NHS Foundation signed the contract with the Integrated Health Projects team following the signing of a land deal at the Whyndyke Farm site, just off the M55.
Building work will begin on site in April so the 154-bed facility known as The Harbour can open in Spring 2015.
Mark Thomas, Regional Director, IHP, said: “The unit will greatly enhance the treatment on offer to patients during their much needed recovery.
“The combined expertise of the trust and our team will ensure The Harbour is a leading mental health facility that Lancashire can be proud of.”
The Harbour development is part of the trust’s on-going commitment to modernising inpatient services and improving the quality of care it delivers.