One replied: "If I ignored US history & current climate of police lynching us, this "joke" would be hilarious."
Another called it "racist garbage".
DeGeneres quickly hit back to defend herself.
The 58-year-old tweeted: "I am highly aware of the racism that exists in our country. It is the furthest thing from who I am."
This isn't the first time the host has landed in hot water over what's been labelled a tone-deaf joke.
Last year, in a parody of Nicki Minaj's new sitcom, DeGeneres aired a sketch on Ellen showing a black family whose backsides were so ridiculously enlarged that they got in the way of everything - even just sitting down to watch TV.