Beddau Library, near Llantrisant, closed in June 2014 due to council cuts - but locals got together to make sure it could stay open.
Volunteers will run it full-time to ensure that doesn't change.
Sarah Powell went to see the ribbon being cut...
Watch the report below:
The volunteers hope the new library will continue to be a "hub" for community events like yoga classes and after school activities for the local children.