Independent provider Care UK has won a five-year contract for healthcare services at Wormwood Scrubs prison in West London.
The firm will provide primary care, dentistry, optometry, physiotherapy and podiatry services.
Meanwhile, mental health services will be subcontracted to Barnet, Enfield and Haringey Mental Health NHS Trust.
The contract was previously held by Central London Community Healthcare NHS Trust with mental health services subcontracted to Central and North West London NHS Foundation Trust.
The contract begins in April and was awarded by NHS England in December.
It will be worth £112m if a two-year option to extend the five-year contract is agreed.