The pregnant DJ will host her very last show on Friday, 22 May, before handing the reigns over to Official Chart Show host Clara Amfo.
We already knew it was going to be a very emotional day for the star, and now she's revealed the tears are already flowing and she hasn't even left the house thanks to son Rex, two.
Fearne tweeted around 8.30am: "My son just looked at my rather over the top dress I'm wearing today and said, 'Mummy, princess.' Tears have started before I leave the house."
The 33-year-old has been thanking fellow DJs for their warm wishes on her last show including Nick Grimshaw, Jo Whiley and Edith Bowman.
She announced in February her intention to step down, saying: "It has also been a time of big decisions and one I want to share with you now. After much time and careful thought I have decided to leave Radio 1 after ten amazing years.
"I have had the most incredible decade broadcasting on Radio 1, meeting wonderful people, helping break artists and watching live music from the world's best."
Fearne and husband Jesse Wood will welcome their second child this year.
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