Jordan North and Vernon Kay also made the final of the ITV show.
Ant and Dec announced the winner during Friday's live final.
The final three will battle it out to be crowned the first King or Queen Of The Castle.
Giovanna's close pal Emma Willis came up with the suggestion.
Here are five things we learned about the Duchess after her Happy Mum, Happy Baby podcast interview with Giovanna Fletcher.
Kate was speaking on Happy Mum, Happy Baby with Giovanna Fletcher – in her first ever podcast interview.
“On Wednesdays we wear breast pumps.”
Her older son's eyes changed from green to brown 👀
Does your toddler do this?