Ian Toothill believes he is the first cancer patient to scale the world's highest mountain and the Owls fan planted a Blades flag at the summit for charity after reaching the top on Monday.
The 47-year-old personal trainer has raised almost £31,500 for Macmillan.
He tweeted: "Nothing to see here, just some cancer dude [Sheffield Wednesday] fan on the summit of Everest with a @SUFC_tweets flag."
Mr Toothill, originally from Sheffield, lives in Willesden Green in London and has climbed in the Himalayas.
He was diagnosed with bowel cancer in June 2015 and told in early 2016 that he had beaten the disease, but later found out it had returned.
He said he has been told he has "just several months left to live".
Speaking in February, he said: "I'm determined to prove anything is possible."
He reached the top of the North Col route on 16 May and the summit of Everest on 5 June.
Mr Toothill was accompanied part-way of the climb by Leslie Binns, from Rotherham, who abandoned his climb to the summit after saving the life of a fellow climber last June.
Writing on his GoFundMe page, he said: "I'm determined to prove anything is possible, no matter what your situation.
"I also want to inspire anyone living with cancer to go and do that special thing they've always wanted to do. Of course, that thing might not be climbing a mountain. It could be finishing that book you've always said you would write, learning a new skill, or taking that dream trip.
"I've previously climbed in the Himalayas for three months, and I've walked across Iceland, solo and unsupported. Climbing Mt Everest would be the pinnacle of my adventures, as it's been a dream since I was a child, and on my bucket list as an adult."
To donate to Ian's cause, click HERE.