Arthur Medici died in hospital at the weekend after being bitten while boogie boarding off the peninsula - which is a popular tourist destination in the US state of Massachusetts.
Posting on a webpage raising funds for the 26-year-old's family, one person wrote: "Arthur was a very happy young man.
"He loved life, he was an active member of a Christian church, devoting his life to the Lord...
"He was always joyful and willing to help others, even going as far as feeding the homeless.
"Our lives are never going to be the same without him.
"His laughter filled our home and he will be greatly missed by us all."
Mr Medici had lived in Revere, Massachusetts. He had been studying engineering part-time at Bunker Hill Community College in Boston.
He moved from Brazil to the United States two years ago and had been engaged to be married.
The incident is the second shark attack in Cape Cod this year. Last month, a 61-year-old man suffered serious injuries fighting off a shark in nearby Truro.
A spokesman for a restaurant near Boston where Mr Medici worked described news of his death as "terrible".
Rich Jeffers from The Capital Grille in Burlington also said: "Just like everybody else, we're shocked and saddened."
There have been three fatal shark attacks around the world so far this year, according to the Florida Programme for Shark Research.
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