The British presenter is worried the Revolutionary Road star will leave her speechless when she hosts the red carpet at the BAFTA Awards on Sunday.
She said: "He is absolutely gorgeous and even better looking in the flesh. Oh my God, yes! I'm slightly concerned I'll just stare at him and won't be able to speak. Which really wouldn't be cool!
"I got 0.5 seconds with Leo at the Golden Globes last month so I'm hoping for a good five minutes this time.
"Five minutes and maybe something juicy from him - and an email address. LeoDiCap@mac.com or something."
Leonardo, 34, isn't the only star attending the prestigious ceremony Fearne admires - she also hopes to meet 'Doubt' actress Meryl Streep, Brad Pitt and his partner Angelina Jolie.
She added: "Meryl Streep is amazing - I worship her. I'd be over the moon to meet her, even just for 30 seconds. And I met Brad and Angelina briefly at the Globes. They are like these totally non-human, shiny, beautiful creatures."
Brad and Angelina have been named in the Leading Actor and Leading Actress categories respectively for their roles in 'The Curious Case of Benjamin Button' and 'Changeling'.
The Orange British Academy Film Awards take place at The Royal Opera House in Covent Garden, London, and will be hosted by Jonathan Ross.