MOUNT PLEASANT, S.C. — As political rehabilitations go, few can match what happened to Mark Sanford on Tuesday night.

Mr. Sanford, the former South Carolina governor once so tarnished by a spectacular lie about an affair that few expected him to recover, is now headed to Congress.

About 55 percent of voters in South Carolina’s First Congressional District forgave the man who turned “hiking the Appalachian Trail” into a euphemism for infidelity, giving him a nearly 10-percentage-point win over his Democratic opponent, Elizabeth Colbert Busch.

In his victory speech, Mr. Sanford promised to be a “messenger to Washington, D.C.” Then, after introducing one of his sons and his fiancée, Mariá Belén Chapur, who had just flown in from Argentina, he spoke of the redemption he had found on the campaign trail.