Whitewaves Care Home in Seal Road, Selsey, is understood to have shut in January.
The residents have been moved out, the council said.
The Observer made several unsuccessful attempts to contact operator Plantinex Limited this week for comment.
In a statement, a county council spokesman said: “West Sussex County Council staff worked closely with residents and their families, to support residents at Whitewaves care home to move to suitable, alternative accommodation, due to concerns about care and support.
“We are continuing to work in partnership with the Care Quality Commission and residents’ families to review the concerns, as the safety and wellbeing of the residents is of paramount importance.”
The spokesman added: “We have supported eight residents to move to suitable, alternative accommodation.”
It is the second care home to close in Selsey in less than a year, after Ashbourne Care Home shut in May, 2017.
Ashbourne’s owner told residents the home was no longer financially viable and they were given just a month to find somewhere else to live.
Some were placed in Whitewaves, prompting some concern, understood to have been from relatives, that they were moved to a home that was rated as ‘requires improvement’ by the Care Quality Commission (CQC).
Responding to the concerns, a West Sussex County Council spokesman said at the time that families were advised to check CQC ratings before deciding where to move their relatives.
A council spokesman said at the time: “Placements were arranged for some people at Whitewaves care home. These were at the specific request of those families.”
A CQC spokesman confirmed it was aware of the situation and was working with West Sussex County Council.
Are you a relative of someone who lived at Whitewaves who has concerns? Ring the newsdesk on 01243 534166.