Greg broadcast himself recording a voice message to the royals, explaining that they had just 10 minutes to get the video to one million views.
“If that happens then CBeebies will upgrade him to a full Bedtime Story and he will be in the bedroom in amongst the greats,” he said.
A short time later, the video appeared as an Instagram story on the @princeandprincessofwales account, alongside the caption “nice PJs, Calum”.
It shot past its target within the following 10 minutes.
Calum was congratulated by fellow Radio 1 presenters, and Greg thanked the prince and princess for giving the campaign “the final push”.
CBeebies also replied, telling Calum: “See you in 2026.”
Princess Catherine was the first royal to tell a bedtime story on the channel, reading The Owl Who Was Afraid of the Dark to mark Children’s Mental Health Week in 2022.
In the same year, she also co-presented a special edition of BBC Newsbeat, also focused on mental health, with her husband.