Emergency services, including the army's Explosive Ordinance Disposal, were called to Asda in Stafford after a suspicious package was found.
A cordon was put in place as a safety precaution on Tuesday night.
After examinations were carried out, Staffordshire Police said the package turned out to be non-suspicious.
A spokesman for the force said: "Officers would like to thank members of the public for their patience and support while this incident was dealt with."
However, Staffordshire Police said it was still probing the incident, adding: "An investigation is ongoing and anyone with any information should message Staffordshire Police on Facebook or Twitter quoting incident number 536 of 27 July, call 101 or alternatively contact Crimestoppers anonymously on 0800 555 111."