13 September 2016 Last updated at 09:29 BST
Emily, who is 11, submitted her short story called The Last Sign to the Jacqueline Wilson Creative Writing Prize, with the author herself picking the winner.
The story reads like it's about an older lady reminiscing about her past before she dies, but the twist at the end is that she is actually a chimpanzee.
The Last Sign will now feature in Jacqueline's new book, which is called Clover Moon.
Jacqueline said: "It was very tough to select just one winner but Emily's story stood out because of its use of language and originality".
Newsround brought Emily and Jacqueline Wilson into the Newsround studio, where they met for the first time and talked about Emily's story.
The competition was open to 7-12 year olds, and they could write about anything they liked, between 750 and 1000 words.

More than 700 students will be taught at the new state-of-the-art Deeside Sixth building.
The £14.6m college is part of a major overhaul of post-16 education by Flintshire council.
First Minister Carwyn Jones will open the facility, based at Coleg Cambria's Deeside campus, on Friday.
In 2013, it was announced that sixth forms at Holywell, John Summers and Connah's Quay high schools were to be axed, with students instead moving to the new college.

Michael Sandford, 20, from Dorking, Surrey, was accused of trying to grab a police officer's gun to shoot Mr Trump at a Las Vegas rally on 18 June.
He pleaded guilty to being an illegal alien in possession of a firearm and disrupting an official function.
Lynne Sandford said she feared Mr Trump would "make an example" of her son.
Sandford had previously pleaded not guilty to charges of disrupting government business and official functions, being an illegal alien, and possession of a gun.
He had been due to stand trial before he signed a plea agreement at a hearing in September.
He is due to be sentenced on Tuesday in Las Vegas.
Sandford's lawyers said he suffers seizures, obsession-compulsion anxiety and autism spectrum disorders.
Mrs Sandford said: "I'm apprehensive and nervous not knowing what the sentence might be.
"Michael is terrified. He phoned me 15 times through the night with severe anxiety over what the judge is going to say to him and the sentence he will be given," she said.
"Although he signed a plea agreement, which should mean he receives between 18 and 24 months, the judge is able to overrule that.
"Michael is afraid that because Donald Trump is now president-elect, it may have some bearing on the judge's sentencing."
Sandford may have faced up to 20 years in a US prison if he had been convicted at trial.
Mrs Sandford said: "Michael is remorseful over what he did. He fears Donald Trump may intervene and choose to make an example of him."
A schoolgirl has beaten thousands of children to get her short story written in Jacqueline Wilson's new book.
[NEXT_CONCEPT]
A multi-million pound sixth form college centralising post-16 education in Flintshire has officially opened its doors.
[NEXT_CONCEPT]
The mother of a British man accused of trying to shoot Donald Trump says he is "terrified" of a lengthy prison sentence.