Having been friends since their teenage years, the pair – who starred in Charlie's Angles together – are clearly very close.
In fact Cameron revealed this week that she knew her pal's other half Wil Kopelman was set to propose after he sought her approval before popping the question.
"I knew Drew was getting married before she did!" the blonde star told InStyle magazine.
The pair were snapped coming out of the Chanel store in Beverly Hills with coy smiles on their faces.
Will was also seen coming out of the store, though it's highly unlikely he saw his beloved in her gown.
Cameron is expected to be bridesmaid when 37-year-old Drew ties the knot this weekend.
It's thought she will wed 33-year-old art consultant Will at her mansion in Montecito, California, which has more than three acres of land.
The couple, who have been dating since February 2011 and got engaged at Christmas, are expecting their first baby later this year.
Drew was previously married to MTV personality Tom Green, and she had a month-long union with bar owner Jeremy Thomas.