The 'Love Me Like You Do' hitmaker is said to have flown into a rage after a fellow Animal Ball attendee stopped her from going into the swanky private area of the bash, which descends on 40 areas across the capital every year, because "only VIPs could enter."
Things between the pair got heated and the woman - whose identity is a mystery - was overheard telling the 29-year-old pop star not to "f***ing mess" with her.
Her aggressive behaviour lead to the blonde beauty retaliating and Ellie was overheard branding her a "bitch" in a foul-mouthed rant with her friends shortly after the row.
Speaking to the MailOnline later on in the evening, Ellie said: "I've never met anyone as mean in my life. If she speaks to me again I will f**king punch her! I swear I'm so mad."
Ellie was joined at the annual ball, which aims to raise money to protect endangered creatures from extinction, by her close pals Anna Friel and Elizabeth Hurley as they all donned extravagant elephant-shaped headpieces all in the name of the charity.
The 'Burn' hitmaker had put on an impressive performance for Princess Eugenie - the granddaughter of Queen Elizabeth - and Lily Cole prior to the blazing row.
The singer had been trying to raise cash for the Elephant Family, Space for Giants, Lion Guardians and the Aspinall Foundation throughout the evening by hosting a table at the Arts Club in London in the hope of contributing to the £2 million charity target.