Vaila has been owned by Richard Rowland and Dorota Rychlik for around three decades.
In good weather it is a ten-minute boat trip from the Shetland mainland, and the island has a coastline spanning around 6.5 miles.
Mr Rowland, a retired solicitor and his Polish wife have decided to focus on their fine art gallery business in Lerwick on the Shetland mainland.
“We’ve had 30 fantastic years here, and we’re getting on in years now, so I think the time has come for someone else to take on the place,” he said
“One just has to be realistic that nothing is forever.”
.Vaila has been home to Neolithic tribes and Norwegian Viking chiefs during its 4,000 years of inhabitation.
In the 1890s, the mill-owning Yorkshireman Herbert Anderton had six-bedroom mansion Vaila Hall built as his summer residence.
The Anderton family sold Mr Rowland bought the entire island, including a three-bedroom farmhouse, a two-bedroom caretaker's cottage and an 18th-century watchtower, after he spotted it in Historic Scotland's Buildings at Risk register.
The sale includes Vaila Hall, an Edwardian mansion featuring stained glass windows, a baronial hall and a stone fireplace.
It has been lovingly restored by the couple who have poured countless resources and time into the island., who are largely based on the island.
There is also the Mucklaberry watch tower which stands overlooking the sea.
Mr Rowland said the couple now intend to base themselves in Lerwick, and keep their Vaila Fine Art premises in the town.
Prior to the Anderton era, Arthur Anderson, the founder of P&O, leased the island in 1837 and established the Shetland Fishing Company there.
Explaining how he discovered Vaila, Mr Rowland said: “We were looking for a project to take on and restore, and had really thought more of the Western Isles or mainland Scotland, and hadn’t really thought about Shetland at all until we saw this.”
The couple gave up their London life and headed to the far north, getting married on the island in 1994 in front of 150 guests there. they bought up the mansion and all its fittings and furnishings – and even the boat used to cross to and from mainland Shetland.
Mr Rowland said: “We’ve had innumerable parties. We used to charter planes to bring guests up here.”
Vaila also features a two bedroom cottage and a three-bedroom farmhouse built in 1894 which has a byre known as the ‘whale house’, where the skeleton of a 42ft sperm whale lies after it was beached on the island in 2000.
The island also currently carries 200 pure bred Shetland ewes, available if any prospective new owner wants to take them on.
Luke French from estate agent Savills said: “The juxtaposition of the dramatic, elemental land and seascape with the exquisite craftsmanship of historic Vaila Hall makes for a quite extraordinary property.
Meanwhile after 30 years on the island, Mr Rowland conceded it will be “quite a wrench” to leave Vaila.
“Vaila is a microcosm of all that is best about Shetland,” he wrote in his book about the island. “Space, peace, natural beauty and wonderful light.”