Orla Sloan, 21, bombarded the footballers with calls, texts, WhatsApp messages and Instagram posts after she briefly dated Mount and he ended their romance.
She used an array of different phone numbers and social media accounts to continue pursuing the players, and made false claims to have fallen pregnant by Gilmour despite them never having sex.
Gilmour told Westminster magistrates court the campaign of stalking by Sloan affected his playing form, as he struggled to sleep and worried about the destruction she was causing to relationships with friends and family.
In the dock on Wednesday, Sloan - a social media influencer, model, and TikToker - pleaded guilty to stalking involving fear of violence or serious alarm or distress against Gilmour, a charge of stalking England midfielder Mount, and a third allegation of harassing Chilwell.
Prosecutor Jason Seetal told the court Sloan met the players, all then playing for Chelsea, at a house party thrown by Chilwell in November 2020.
“Following that, Mr Mount and Ms Sloan slept together once”, he said. “There was communication between them for around six months and Mr Mount decided that the relationship wasn’t going to progress anymore.
“He decided to end contact with Ms Sloan.”
Mr Seetal said Mount then faced a “bombardment of messages” from Sloan, who ignored his requests to stop contact and she set up at least 21 different phone numbers to continue the pursuit.
The court heard on one occasion when she was blocked by Mount, Sloan sent the star a picture of herself buying a new phone number along with the caption “I’m not buying food anymore so I can get more numbers – I will be faster than you”.
“Some of the messages are apologetic, saying ‘I really wanted to say sorry to you, talk to me and let me know how you feel’”, said the prosecutor.
But he said Sloan then revealed her alter ego, telling Mount it is “a character called ‘devil baby’”, and adding: “You and Ben (Chilwell) will be destroyed”.
“Beware of devil baby Mason, I can morph in a second”, she wrote.
The court heard Sloan created an Instagram account, devilbaby_10, dubbing Mount a “criminal”, posting collages of the player with other women, and attempting to contact his colleagues, friends and family.
“He was concerned she had an obsession or fixation with him and didn’t know what she could be capable of”, added Mr Seetal.
In a statement, Mount said: “She knows roughly where I live and where I train. I am worried when unable to contact me she might turn up at my training centre.”
The court heard Sloan also posted collages of Chilwell while attempting to make contact with him, and made a claim online about his sexuality.
Scottish international Gilmour told the court he made the move from Chelsea to Brighton in summer 2022, and found himself being bombarded with messages from Sloan while in an unfamiliar new home and away from his friends and family.
He had messaged her briefly after they met at the house party but then tried to cut off contact, the court heard
However she set about stalking him in summer 2022, claiming online to have fallen pregnant by the footballer.
“Mr Gilmour has never been in an intimate relationship with Ms Sloan”, said Mr Seetal.
Outlining the impact of her behaviour, Gilmour said in a statement: “I was not able to sleep and had to take sleeping tablets on occasions.
“It had a knock-on effect on my performance”, adding that he was left “extremely stressed” and struck by “feelings of panic”.
“For a period of time I was consistently receiving notifications of messages from Orla, or contacted by people she was harassing.
“I was worried not only for myself but also those targeted by Orla.”
Gilmour said he cut off contact with friends and female acquaintances on social media to protect them from Sloan.
Sloan, who lived in Westminster in central London but gave an address to the court in Exeter, was released on bail by District Judge Neeta Minhas until a sentencing hearing on June 20.
The judge warned Sloan that her case could be dealt with in the crown court, and she could face a prison sentence.
“The starting point for one offence crosses the custody threshold, and it was targeting of three different people”, she said.
Sloan admitted stalking Mount from June to October 2022, harassing Chilwell at the end of October 2022, and stalking Gilmour between September 10 and October 28, 2022.