The show is due to open to the public at the London Palladium later this week for previews, ahead of its official premiere later next month.
However, issues caused by its 'ambitious' staging, bosses have now decided to cancel this Thursday and Friday's performances, with the first preview now taking place on Saturday 1st March.
In a statement, producer Rebecca Quigley said: "After much careful thought and discussion we’ve decided that we need to take some more time to work on technical aspects of I Can't Sing! at the Palladium.
"As audiences will soon see the production is hugely ambitious, and the volume of installation and scale of the set means that technical work has taken slightly longer than could have been anticipated to make the show audience-ready.
"The entire I Can’t Sing! family cannot wait for everyone to see the show and we thank everyone for their patience and understanding."
Reseating options will be offered to ticket holders, who should contact their point of purchase for further details.
I Can't Sing! is a satirical take on The X Factor, starring former EastEnders actor Nigel Harman as a fictional version of Simon Cowell and Cynthia Erivo as Chenice, a hopeful who auditions for the talent contest.
The project is backed by Cowell and co-produced by his firm Syco Entertainment.