The Pistol Annies singer was due to perform at the 'Jam in Valley' festival in Varysburg, New York on Friday (July 6), but had to axe the show on orders from her doctor.
Lambert has also cancelled a number of concerts planned for this month, according to a post on her official website reading: "Due to overextending her voice, Miranda has been placed on vocal rest.
"She's under the care of her doctor and she hopes to return to the road next weekend."
Lambert is married to The Voice judge and fellow performer Blake Shelton.
The country singer won the 'Female Video of the Year' prize at the CMT awards in June.
Watch Miranda Lambert's video for 'Over You' below: