Selena Gomez Jimmy Kimmel wave phone

She's got a lot to smile about these days!

Selena Gomez gave us a wave and a grin as she arrived at the studio to tape an appearance on Jimmy Kimmel Live!, and the singer dished about everything from her recent 21st birthday to her newborn baby sister with the talk show host!

"I had a really big party. It was really fun. I wanted it to feel like you were in a genie's bottle, so I had the blue curtains and pink curtains, candles, and belly dancers. I had girls that were dressed up like mermaids. And I was so fascinated by them. I basically spent my whole party with them the whole night," she revealed during the sit-down.

So how is life as a new big sister?

"I'm the babysitter that likes to cuddle and sleep with her and the moment anything happens down there, or she throws up, I'm like 'here you go, Mom. Thank you'," she joked.

It has been a big week career-wise for Miss Gomez!

Not only did she just take home the Fan Favorite Album Award and the Most Anticipated Tour Award at the Young Hollywood Awards, but her newest album Stars Dance is #1 on the Billboard charts!