The 26-year-old is unrecognisable after switching up her brunette locks for a blonde 'do.
Taking to Instagram, the reality star shared a snap of her new hairdo with the caption: "Good morning."
Many fans quickly commented that they didn't realise it was her posting the photo as she looked so different.
One user commented: "I was scrolling and thought geez Kate Hudson looks amazing today and then realised oh my lord it’s you. Looking amazing!"
Someone else wrote: "You look like Mandy Moore in her prime here! Beautiful."
Another user commented on Brittney's fuller looking lips, writing: "Lips look awesome", to which Brittney responded, "Thank you."
A cosmetic clinic also commented, saying Brittney looked "gorgeous" and she responded: "LOVING my lips."
"I love your hair this colour," one user added, while another commenter wrote: "Oh my god that’s you! I was thinking why is there a Brittney on my insta account - then I realized it was you!! HOOOOOOT!"
Brittney first appeared on the Honey Badger's season of The Bachelor in 2018, and has been on two seasons of Bachelor in Paradise.
The reality star updated fans after Paradise finished to reveal she and Jackson Garlick, who left the show together, were no longer dating.
She wrote: "I’m here for my final update: [Jackson] and I aren’t together but he is an amazing guy... we did catch up on the outside, I did meet his friends and family and we had good times.
"Unfortunately, life gets in the way and we are now just friends. I am so happy that I had this experience and wouldn’t change anything."
She added: "Thank you to all the amazing people that I have met throughout it all, you have made it one hell of a journey!"
Jackson shared his own update, revealing he was to blame for their relationship breakdown.
"It’s difficult to put into words what it was like watching the show back. [Brittney] is such a great girl and is always the life of the party.
"Unfortunately after getting back to Australia, we found it difficult to see each other. Brittney did come to my birthday (and made the effort) in December 2019 and met all of my friends and family. She received rave reviews from all."
He continued: "I’m mostly to blame for the lack of effort to keep our good thing going because I came straight back into preseason training and couldn’t travel to see her.
"She deserves the world and I wish her so much happiness. Until next time Littney x," he finished.