The empty three-storey building at 100 Pleck Road, backing onto Walsall Manor Hospital's car park, is on the market for £499,999, with the agents suggesting it could be converted into homes.
Although it sits on the edge of the hospital site, the building is not owned by Walsall Healthcare NHS Trust.
The Online Property Agency, from Birmingham, describes the building as a "spacious detached property with great potential situated in just walking distance of the Walsall Manor Hospital".
"This grade II listed property has a variety of uses (STP) such apartments/flats or even a beautiful family home," the listing says.
"The property is well presented from the outside and still retains some pleasing period features externally."
The red brick building was built between 1898 and 1900, and was the office for Board of Guardians of Walsall Poor Law Union which ran the Walsall Union workhouse at the junction of Pleck Road and Moat Road.
It features painted stone dressings, slate hipped roofs with pierced and crested ridge tiles, and a tower in one corner.
The building has had Grade II listed status since 1995 for its special architectural or historic interest, but has stood empty for many years. Many of the surrounding buildings that once made up the workhouse were demolished in 2011.
Speaking about its interior, the Historic England entry says: "Most of the original interior features remain intact. Glazed tile dados; joinery including panelled doors; chimneypieces; arched screen in entrance hall with stained glass; staircase with ornate wrought and cast-iron balustrade, carved newel and moulded handrail; board room on first floor with moulded plaster panelled coved ceiling and modillion cornice with egg-and-dart frieze."
A spokeswoman for the agency said the firm was selling it on behalf of an investment company, adding that the building is a "very interesting Grade II Listed building with land on the side with huge potential and may be suitable for various uses subject to planning".
In total the site covers 0.226 acres, with an internal area of 7,500sqft.
"It would be fantastic to sell this gem of a property to a local person or developer who can restore this back and improve the local area," she added.
View the listing here.