The Social Network star proposed to Biel in December (11) and the couple celebrated its love during a private bash at the home of Timberlake's longtime friend Estee Stanley.
Guests dined on gourmet appetisers prepared by Wolfgang Puck Catering and a slew of celebrities were on hand to show their support - Amy Adams, TV host Ellen DeGeneres and her actress wife Portia DeRossi, and Timberlake's former N'Sync bandmates Lance Bass and JC Chasez all attended the party.
Biel donned a leopard-print halter dress with a hot pink belt for the event, according to UsMagazine.com.
A source tells the website, "Jessica and Justin were mingling both separately and together throughout the party. Jessica seems to be very close with Justin's friends and vice versa. You can see that they have been dating for a long time and really know each others friends and family well. The party was a fun celebration and a preview of what's to come with the wedding."