Dressed in all black with her hair tied up in a bun, the “Someone Like You” singer, 25, snuck into the Belvedere Vodka-sponsored event through a back door with Konecki, 39, a source tells PEOPLE.
The starry audience included Emma Watson, Eddie Redmayne, Suki Waterhouse and Jonathan Rhys Meyers, but the couple spent some extra time mingling with Sting and designer Philip Treacy while enjoying dinner in the back of the room.
“Her skin was radiant and she seemed very happy to be out,” adds the source. “Simon kissed Adele on the cheek and had his arm around her waist at many times of the night.”
Lady Gaga performed her hits “Artpop,” “Poker Face,” “Dope” and “Do What U Want” at the intimate bash.
— Melody Chiu