George Walton was an Episcopalian. The Episcopal Church is the American province of the Anglican Communion. Some sources identify Walton specifically as an "Anglican," rather than an "Episcopalian," which is the more common denominational name by which American Anglicans were known, even during late 1700s.
He was identified as an Anglican by the Georgia Historial Society. (Source: Ian Dorion, "Table of the Religious Affiliations of American Founders", 1997).
From: Robert G. Ferris (editor), Signers of the Declaration: Historic Places Commemorating the Signing of the Declaration of Independence, published by the United States Department of the Interior, National Park Service: Washington, D.C. (revised edition 1975), page 142:
Assigned first to the Rosney Cemetery in Augusta, his remains now rest at the Signer's Monument in that city.
Note that numerous sources and authoritative references have been consulted in order to ascertain the religious affiliation of the American Founding Fathers. Note that the excerpts and references mentioned on this page are not the only references used in order to identify this person's religious affiliation.