Diaz, 45, turned heads in a dazzling red sequinned wrap dress by Jenny Packed, along with a matching, bold lip, black bag and gold earrings.
Her 39-year-old Good Charlotte rocker husband went all black in a suit and bow-tie.
Other celebrities who on the guest list for Paltrow and Brad Falchuk's glamorous engagement party includded Reese Witherspoon, Kate Hudson, Jennifer Aniston and Liv Tyler.
This article originally appeared on WHO.