Demi Lovato Celebrates Birthday in London with Ariana Grande

Demi Lovato is celebrating her 27th birthday in style.

The singer was busy on Instagram posting stories, videos and pictures in London with Ariana Grande and talent manager Scooter Braun. Lovato attended Grande's concert at the O2 Arena.

Demi shared one video of the show prayer before Ariana's show where they all wished her a happy birthday. "This was too sweet not to post...before show prayer they did this for my bday. I'm so proud of you @arianagrande. You f***ing killed that!!! I love you tons," she captioned the video.

She also posted a video of Grande, Braun, and a group singing to her, and a selfie with the caption, "Last day as 26."