The West Kensington High Street branch of Street Kitchen was subject to the unflattering reviews on Tripadvisor.
Out of a total of 53 reviews, 20 of them rated the burger restaurant "poor" or "terrible".
Two reviews said the restaurant was "average," while six rated it "very good".
But 25 diners said it was "excellent".
The restaurant offers burgers, seasoned fries and unlimited soft drink for £15.
There is a raft of burgers to choose from, including beef, lamb, chicken, vegetarian and vegan options.
One reviewer fumed about a "tasteless" burger, describing it as the "worst burger ever".
Faiza CJ wrote: "If you like burgers rare to medium rare don’t even bother going.
"Their policy is to serve their meat well done which results in burgers which are tasteless and hard as a brick. Honestly it was the worst burger ever.
"Which is sad because the service was great and to be commended. Why a world famous chef would put his name to this is beyond me."
De M said: "This was the worst burger I ever had! The burger was terrible, the egg was so over cooked, the bacon was chewy and half raw, the burger was over cooked and really dry.
"We waited an hour for the food to arrive from when we ordered and the restaurant was half empty."
Another reviewer, Nick S, branded Gordon's restaurant simply: "Hype!"
He said: "The burger was incredibly salty and served on a metal tray covered in greaseproof paper.
"What’s happened to plates Gordon? Who wants ripping greaseproof paper under their food?"
However, others raved about the place and its "superb" burgers.
Wendy Morgan said: "We were very impressed. I wasn’t sure what to expect after reading some earlier reviews but my husband and our two friends just ate the best burgers we have eaten in a really long time.
"From the start, service was on point, no waiting around for drinks and that lead onto our food.
"Delicious onion rings followed by three wagyu burgers and one vegan burger with sweet potato fries!
"Everything was cooked so well."
Others commended staff's "great service," with one reviewer saying it was "second to none".
Gordon Ramsay and Gordon Ramsay Restaurants have been contacted for comment.
The burger bar charges £15 for fries, a burger and unlimited soft drink