The 31-year-old bass player was seen making flirtatious gestures behind singer Cheryl and boyfriend Liam Payne as they were interviewed by Brits host Jack Whitehall.
Many people watching the British awards show commented online about the "random drunk woman", as did several news outlets, before she was identified as the singer and bass player from the hit Californian band.
Este, who wore an eye-catching floral crown for the star-studded event matching her sisters' Danielle and Alana, playfully gestured to someone unseen, mouthing "call me" while cheekily winking to the viewers at home, as Cheryl and Liam remained oblivious.
After news reports alleged Este was making fun of the singer and her beau, the star gave Cheryl a call to clear things up, insisting she has "no beef" with the Fight for this Love hitmaker, during an appearance with her sisters on Nick Grimshaw's BBC Radio 1 breakfast show on Thursday.
"Hi this is Este Haim calling. I'm in a band call Haim with my sisters. We... wait before anything, congrats on the baby, big Mazel," she started. "I happened to be sitting behind you last night at the Brit Awards and had an amazing time however some people on the internet are claiming I may or may not have been thumbing my nose at the situation in front of me. But I just wanna let you know there's no beef and I'd like to invite you to my show at Alexandra Palace on June 13th (it's the 15th her sister corrected in the background) 2018... it's early and I haven't slept.”
“Big kiss, lots of love there's no beef we're all friends here. Big hug, big kisses, call me, I'll text you my number," she said, finishing her extra-long voicemail.
Cheryl has yet to respond to Este's voicemail.
After Este’s Brits antics, online news outlet Lad Bible tweeted: "Drunk woman behind Liam and Cheryl at Brit Awards makes viewers p**s themselves laughing."
Later Este retweeted it, adding: "Not drunk, just living my truth."