The singer attended the central London event to celebrate the release of Lip Booms, a collaboration with cosmetics brand Make Up Academy.
However, Burke's team drafted in extra security after a TwItter user bombarded her with a series of threatening messages, claiming that they would be present at the launch.
The messages sent by the user included: "I'm coming, and I'll murder you!", "I'm going to kill you tonight", "gonna stab you", and "prepare to die".
Burke's mother Melissa Bell and brother David both spoke out against the individual, with the latter warning: "I'll be there tonight, I DARE you to try bring harm to Alex... And see what will happen! Don't f**k with us! (sic)"
A source told Metro that the 23-year-old had been "freaked out" by the abuse, which prompted her team to contact the police.
"The police agreed to meet Alex at the entry of the club when she arrived and escort her in," they said. "Her own team weren't taking any chances. Her management decided to draft in extra security to be by her side all night.
"It could have been nothing more than a disgusting bluff but no-one was willing to take any chances after Leona Lewis was attacked a few years ago. Every threat has to be taken seriously - if something happened, Alex's team would never forgive themselves."
The Twitter user has since had their account on the micro-blogging website suspended.
After the event, also attended by Burke's boyfriend Jermain Defoe, she wrote on Twitter: "Had an amazing time at my launch tonight! Thanks 2everyone who came out&supported me. Means so much. Tonight was unreal. I'm so happy!"
Last month, it was revealed that the X Factor star's family identified and confronted a man who had threatened to stab Burke while they ate in the same restaurant.
> Alexandra Burke films 'Let It Go' music video - pictures
Watch Alexandra Burke's 'Elephant' video below: