Wrapping their arms around each other and smiling sweetly for the cameras, they put on a loved-up display for their first official public outing.
"Now, it's out. It's done," 19-year-old Chloe told E! News on the red carpet. "It's real. We're together and that's it!"
Looking the spitting image of his dad David, the aspiring photographer swept his hair into a neat quiff and rolled up the sleeves of his jacket.
He completed his look with a white shirt, black tie and brown suede boots.
Kick Ass star Chloe put on a rather racy display in a black dress with lace detail which flashed her bra and plenty of flesh.
Pictures from inside the bash show Brooklyn proudly throwing one arm around Chloe's shoulder and pulling her in close.
The PDA comes as Chloe revealed how Brooklyn has been given the seal of approval by her "super protective" brothers.
She told James Corden: "They're super protective, but I kind of like it.
"They like him so they're nice to him now. Now that I have a boyfriend, they correspond [with each other] secretively.
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"We were all at dinner the other night and I caught my boyfriend texting my brother. ... Maybe it's like, they're intimidating each other on text message."
She said: "At the start it was like, 'What's he want? What's he looking for?'
"I'm like, 'Guys, I'm the older woman. It's OK here. I'm in control.' "
Chloe recently admitted she gets on well with Brooklyn's famous parents, David and Victoria Beckham.
She said: "He's a great dad, she's a great mother. They genuinely are very good parents that's what matters most, they made a pretty son."
