The club, based in Horsham, provides support to over 50 stroke survivors every week across West Sussex.
Over £325,000 was raised to pay for the building and landscaping work.
The extension means more members can join, particularly stroke survivors in wheelchairs. There is a therapy room where members can receive treatment in the privacy of a dedicated area as well as a new landscaped garden area.
Here is a selection of pictures by our photographer Steve Robards from the opening.
And you can read more from the ceremony, including the thoughts of Chris Tarrant, here.
The extension means more members can join, particularly stroke survivors in wheelchairs. There is a therapy room where members can receive treatment in the privacy of a dedicated area as well as a new landscaped garden area.