The Come & Get It singer surprised many when she unexpectedly hit the red carpet at the Los Angeles ceremony. It marked her first public appearance since August (16), when she abandoned her tour to deal with anxiety and depression caused by her struggle with autoimmune disorder lupus.
Fellow popstar Ariana told ETOnline she was so happy to see Selena back in the limelight that she almost became emotional.
"I literally almost cried when I saw her," she said. "I haven't talked to her in a long time. So, I don't know what's going on, but I gave her a huge hug and she looks beautiful. And I'm so happy that she's here. I'm happy to see her out and about."
The Side to Side singer also said she gave her a really tight hug when Selena hit the red carpet and praised her red Prada gown, adding, "She looks like a princess."
Ariana went on to win the Artist of the Year prize at the ceremony but Selena stole all the headlines with her impassioned acceptance speech when she received the Pop/Rock Female Artist award.
"I think it's safe to say most of you know my life whether I liked it or not. And I had to stop," she said. "Because I had everything. And I was absolutely broken inside. I kept it all together enough to where I would never let you down, but I kept it too much together to where I let myself down.
"I'm not trying to get validation, nor do I need it anymore... I have to say thank you so much to my fans, because you guys are so damn loyal, and I don't know what I did to deserve you. But if you are broken, you do not have to stay broken... this is for you".
Footage from the ceremony showed Lady Gaga celebrating Selena's win, while E! Online insiders say Niall Horan, Ariana and Hailee Steinfeld all showed their support once she'd stepped off the stage. Her best pal Taylor Swift also shared an Instagram story of her yelling with pride at her television while Selena's speech was being broadcast.