3 March 2017 Last updated at 14:07 GMT
Romeo, aged four, asked his father Charlie Makaveli if he could go to school dressed as the leader of the Autobots, Optimus Prime.
It took his father a week to construct the outfit out of cardboard, paint and glue.
Mr Makaveli, a florist from Romford, east London, said his son got a big cheer when he showed how his outfit "transformed".
So far, the video has been viewed about 50,000 times on Mr Makaveli's Facebook page.
A father really went to town when his son asked for a Transformers outfit for World Book Day.