Co-ordinator Sandra Davis said the free service had outgrown its previous location at the Shepparton Police Station.
Mrs Davis said there would be a roster of 13 volunteer justices of the peace based at the library.
The service operates between 10am and 1pm Monday to Saturday, with no appointments required.
Justices of the peace are independent and objective community members who have demonstrated a commitment to actively providing vital justice services to all members of the community.
They are responsible for signing, witnessing and certifying legal, financial and administrative documents to verify that copies are genuine or that signatures are made freely and truthfully.
For example, justices of the peace may witness an affidavit for use in court, witness a statutory declaration, certify a true copy of an original document or certify a person’s identity. They can also sign and witness power of attorney, medical decision-making documents and basic wills.
Mrs Davis said such was the demand for the service locally, some volunteers were signing documents out of hours at home.