The pair was seen together watching Kings of Leon on Sunday. Goulding wore an oversized jacket and hoodie, while the One Direction member stayed low-key with a hoodie and sunglasses.
Horan leaned in to kiss Goulding, 26, while they awaited Kings of Leon's encore. They were shielded from photographers by their bodyguards.
Goulding split from her boyfriend Jeremy Irvine last month, and she has been spotted looking cozy with Horan a few times since.
He had told a magazine in the past that he was attracted to Goulding.
"I'll say one thing: Ellie Goulding - wow. She's absolutely amazing looking."
The two also flirted on Twitter, as Horan complimented her on her voice.
Niall even shared his infatuation with Ellie as far back as July. He tweeted, ”Just listening to some @elliegoulding! What a talent she is! Beautiful voice !”
She responded, “I knew you loved me hahaha”
Some Directioners will be disappointed if the relationship is serious enough to put her on the red carpet for the band's "This Is Us" premiere.