Emily Brown, of Riceville, was shopping Friday night at a Walmart in Cleveland, Tennessee, when she discovered the blade, the television station reported.
"Some idiot thought it would be 'funny' to place a blade underneath the handle, in the hopes someone would get hurt," Brown posted on Facebook early Saturday. "Luckily, I'm the weirdo who never grabs the handle anyway, lol ... So, I wasn't hurt."
Brown immediately found a manager, who safely removed the 4-inch blade, WTVC reported.
In a statement, a Walmart corporate spokesman said the company was "appalled."
"We are aware of the situation and appalled that someone would do this in our store," the spokesman said. "While we've found no further signs of tampering, we inspected the other carts to help ensure the safety of our customers and associates."