“John Lewis helps themselves to my picture book,” he tweeted on 16 November.
Riddell’s book was published in 2011 and follows the story of Jim, who befriends a loud, snoring monster - Mr Underbed.
Riddell’s video has been retweeted nearly 2,000 times in less than 24 hours and many were shocked with the similarities.
Speaking to the Guardian, Riddell said: “The idea of a monster under the bed is by no means new but the ad does seem to bear a close resemblance to my creation – a big blue unthreatening monster who rocks the bed and snores loudly.
“Needless to say, I think Mr Underbed is a lot more appealing than Moz, but of course, I’m biased.”
Responding to the criticism, a John Lewis spokesperson told HuffPost UK: “The story of a big hairy monster under the bed which keeps a child from sleeping is a universal tale which has been told many times over many years.
“Ours is a Christmas story of friendship and fun between Joe and Moz The Monster, in which Joe receives a night light which helps him get a good night’s sleep. The main thrust of our story is utterly different to Chris Riddell’s.”
HuffPost UK has contacted Riddell for further comment and will update this piece upon his response.