The five are among the buildings local advocates has been pushing to landmark ahead of a proposed rezoning of the area.
Of the 16 people who provided testimony at the hearing, including representatives for the owners of four of the five properties, not one person spoke against designation.
But the site has a stop work order and nearby residents claim to have seen workers on site recently in violation of it.
No injuries were reported and the cause of the fire is under investigation.
The efforts of a coalition of preservationists, scholars and fans of Whitman got a boost Monday from six New York City Council members who signed a letter of support for designation.
The proposal includes nearly 30 individual buildings, three historic districts and one scenic landmark.
The Landmarks Preservation Commission Tuesday designated two commercial buildings on Montague Street, a jazz-age skyscraper and a building resembling a classic temple.