He presented a symbolic giant cheque to hospice chief executive Grazina Berry for the work starting during September, which means the number of beds available in the ward temporarily reduced.
Barry has had personal family experience of the hospice in Havering-atte-Bower.
“Both my mother-in-law and my father-in-law were cared for at Saint Francis,” he said.
“I was so impressed with the respect and care shown to them — it really did make a difficult time a bit easier.
“The compassionate care the hospice provides couldn’t exist without support.”
Construction is expected to be finished next March with bed availability on the ward reduced from 18 to 11 for the time being, although seven beds are being moved to a new ‘home service’ to ensure continuity.
“The hospice needs to provide more services than it currently does to meet the growing demand,” Barry added.
“Saint Francis is such a special place. People’s introduction starts at a time when there are more tears than smiles.”
Barry is founder of Matchroom Charitable Foundation, which has donated £1million so far to help keep the hospice up and running.
He made his fortune in boxing, snooker, darts and pool, while helping develop new sports and increasing prize money as chairman for the Professional Darts Corporation and the World Professional Billiards and Snooker Association.
His latest gift to Saint Francis is also going towards redesigning the lounge and entrance to create a more welcoming and functional space and a quiet room for relatives.
Saint Francis is a charity that employs 150 nurses, doctors and specialist healthcare staff who are supported by 800 volunteers.
It gives help to 4,000 people in the London boroughs of Havering, Redbridge and Barking and Dagenham, as well as Brentwood and parts of west Essex.
The hospice provides services free to people with life-limiting illness such as cancer, heart, lung or motor neurone disease.
