The pair booked into the exclusive hotel George V for a three-day break to soak up some Christmas atmosphere.
But the former Miss Ireland was left gobsmacked after her other half went down on bended knee and surprised her with a sparkler at the Eiffel Tower. "She had no clue he was going to propose. She was absolutely thrilled and just couldn't believe it," said a pal.
The happy couple texted close friends and family yesterday morning to break the good news of their engagement.
Her good pal Kristi Kuudisiim, who works at Andrea's agency, said she was "thrilled" with the news. "It's fantastic news and she's just savouring the moment. She's absolutely thrilled," she said.
The pair have been dating for almost two years and Rob was her first serious relationship since she split from her former husband PJ Mansfield in December 2009.
The brother of actress Holly White, Killiney native Rob is well-known on the social scene and was considered one of Dublin's most eligible bachelors before Andrea nabbed him.
They started dating in April last year and moved in together not long afterwards.
The former Miss Ireland has done her best to keep the relationship under wraps and rarely talks about her other half to the media but the sociable pair have been regular fixtures on the Dublin scene.
Well known-beauty Andrea, who took part in RTE's Celebrity Bainisteoir, first confirmed that she had split from her husband in March 2010.
Since splitting from PJ, she has moved out of their Citywest pad and went on to set up her own agency in Fitzwilliam Square and recently started bootcamps teaching aspiring beauties how to become models.
She also runs Miss Universe Ireland and has been credited with discovering top stars like Rosanna Davison, Rozanna Purcell, Kristi Kuudisiim, Pippa O'Connor and Hannah Devane.