Peter Soul, 68, from Lakeside in Earley, took on the charity challenge last month, raising £2,900 for the Robbie The Robot Appeal after he was diagnosed with prostate cancer in 2009 and operated on using the Da vinci robot six months later.
He said: "I have achieved so much more than I thought I would, both in the amount that has been raised and how I managed to play the music.
"The good thing about being an amateur is that any mistakes don't really matter and I just kept going.
"I actually really enjoyed it."
Mr Soul performed at South Hill Park in Bracknell across several afternoons and completed the challenge on Thursday last week, raising cash to fund Robbie The Robot, which performs keyhole surgery at the Royal Berkshire Hospital.
He added: "I must thank the staff at South Hill Park for allowing me free use of the recital room and its wonderful Steinway piano.
"Seven afternoons, 21 hours, 32 sonatas, and an estimated half a million notes - I admit that I did some preparation before each afternoon, looking at the more difficult passages, though it was hardly the equivalent of training for the London Marathon or similar.
"But the end result for me was that I came to know all the sonatas better than I did before, and I got through the Hammerklavier sonata - about which even hardened musicans said to me 'surely you're not going to attempt that?', in what I felt was a triumph of sight-reading."
Donations can still be made at: www.justgiving.com/beethoven32