Over 70 members of the local community joined coastguard, fire service and police in a search for her whereabouts.
On Sunday at 1.05pm officers were made aware that a body of a woman had been found in the Aird area of the island.
Police Scotland said the family of Ms MacInnes had been notified.
The death is not being treated as suspicious and a report will be submitted to the Procurator Fiscal, the force added.
A statement issued by Police Scotland read: “The body of a woman found in the Aird area of Benbecula on Sunday, 24 November, 2024, has been formally identified as 28-year-old Shanahan MacInnes.
“The death is not being treated as suspicious and a report will be submitted to the Procurator Fiscal.”
