28-year-old Audrina used to be BFFs with Lauren back in their days filming the hit MTV series and the pair even shared a house together before drifting apart on screen.
Audrina admitted this week that the pair haven't seen each other in years. Nevertheless, she is still over the moon for Lauren on her recent engagement to boyfriend William Tell.
Audrina told US Weekly: "That's amazing. I've never met William... as long as he treats her right and she's happy that's all that matters."
Lauren, 27, got engaged to musician William earlier this month, revealing the news via her website and claiming that she was "beyond thrilled."
The twosome first began dating on Valentine's Day in 2012 and recently moved in together.
Since announcing her engagement, Lauren has been inundated with warm wishes from friends, fans and ex co-stars.
And Audrina isn't the only former cast member of The Hills to congratulate her old pal, as Spencer and Heidi Pratt were quick to send Lauren a message too, believe it or not.
Spencer tweeted: ""@LaurenConrad Sincerely wishing you all the happiness in the world on your engagement. Congratulations!"
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