Mr Stevenson - whose Aberdeen garden is known to many because he fills it each Christmas with festive fairy lights and popular characters such as Snow White and the Seven Dwarves - was honoured for his services to healthcare and charity.
His seasonal makeover of his Ashgrove Road West garden has raised more than £130,000 over the last 27 years for children with special needs.
The 66-year-old worked at the University for 42 years in the biomedical physics department before taking retirement last May.
During that time Mr Stevenson was a member of Professor John Mallard's pioneering team which created the world's first clinical MRI imaging scanner.
He said: "I am really delighted it was such a surprise, I'm still on cloud nine. You don't do these things to get honoured and when it happened it came out of the blue. It's really wonderful!"
Notes to Editors
Issued by the Communications Team, Office of External Affairs, University of Aberdeen, King's College, Aberdeen. Tel: (01224) 272014.
Issued on: 05 January 2010
Contact: Jennifer Phillips