However, as guests entered the Los Angeles Theatre, reports emerged that the "engagement party" was actually a secret wedding - especially after Gwyn's celeb mum Blythe Danner was spotted entering the venue with a Monique Lhuillier bridal dress bag.
"Thank you #ryanmurphy for the most incredible evening to celebrate our (love)", she writes on Instagram alongside a picture from the party.
'@giambattistavalliparis I will never get over my gorgeous dress.
Reese Witherspoon, Jennifer Aniston, Kate Hudson, Steven Spielberg and Demi Moore all also attended, dressed to the nines as they made their way into the party which had a dress code of black tie. @Teamsaltzman thank you. Thank you to all of our wonderful true and dear friends who came to support us.
Having eloped with Chris, Gwyneth says she is treating this wedding as her first and is pulling out all the traditional stops. We feel like the luckiest people on the planet because we have you in our lives.
Paltrow's ex, Coldplay star Chris Martin, was absent from the event.
And Paltrow can't believe her former Glee boss pulled off such a great bash.