The attraction is based on his Gangsta Granny books and will open to the public on May 17.
Six local children were invited to test the ride and became the first to experience it.
The ride smells of cabbage soup and there is Raj's Shop with the infamous Nick n' Mix.
The new multi-sensory ride experience will see guests join the main characters as they attempt the greatest heist in the history of the world: to steal the Crown Jewels. The exhilarating journey will see guests hop aboard a Royal Carriage as they set off on a remarkable tour of London’s Crown Jewels only to be swept-up in Ben and Granny’s exhilarating escapade.
The ride will whizz, twist and spin through the sewers on a 360° special effect laden, wild ride to break into the Crown Jewels vault. Passengers will see, feel, hear and even smell an electrifying and unique re-telling of the Gangsta Granny story.
David Walliams said: “It’s an incredible feeling, I did feel very emotional. I did think ‘wow, how has all this happened’ because the book was written just over 10 years ago, and it’s now famous enough to have its own ride at Alton Towers. I came here as a kid! So, it’s pretty mind-blowing.
“I just loved going on the ride, and I can’t wait to come back with my son and nephew because they are both under 10, I mean they both will absolutely freak out when they get to experience it. “