The singer, who normally remains tight-lipped about her relationship with the hip hop star, grinned as she gave a shout out to her other half in front of a packed audience.
Picking up the Billboard Millennium Award, which was presented to her by her own mother, she said: 'I'd also like to thank my best friend.
'I don’t want to put you on the spot, because I know they’re probably putting the camera in your face right now, but I love me some Jay-Z.'
A host of celebrities recorded messages in tribute to Beyonce, as she took home the Millennium Award.
Lady Gaga, Stevie Wonder, Bono - and even US First Lady Michelle Obama - sung the performer's praises in a pre-recorded segment of the show.
Beyonce then took to the stage for the first televised performance of her new single Run The World (Girls).
The singer shared a hug with her mother, Tina, as she accepted her award and was hailed as a role model for women.
Rihanna and Jay-Z cheered Beyonce from the audience, while former Destiny's Child band mate Kelly Rowland blew her a kiss.
Beyonce thanked Rowland and their fellow band member Michelle Williams during her acceptance speech. She also paid tribute to the original members of the group, LaTavia Roberson and LeToya Luckett.