According to an eyewitness, "They were super cozy and super close."
"She rapped along to lyrics as the DJ played his song 'F-ckin' Problems.' She took his goggles off at one point and put them on herself. She sat next to him the whole time," the eyewitness told Us.
Jenner, 21, and Rocky, 28, reportedly arrived and left the party separately, but that doesn't necessarily mean the duo aren't dating.
"It was clear she was there just to see him," the onlooker added. "As soon as she walked into the party, she asked where he was. He was rubbing her arms at one point later in the night because it got really chilly."
The couple attended the #WeedMapsOasis party, which was presented by West Coast Cure and Brass Knuckles. Jenner reportedly made an appearance at the party with a group of her friends in order to watch Rocky perform.
"When he wasn't onstage hosting and was back in the VIP section, she would sit right by him," the eyewitness said.
The rumored couple has been spending time together since early 2016. Jenner and Rocky have kept the status of their relationship -- or romance -- pretty hush hush, and a source told the magazine in January 2017 that the supermodel was not "in a serious relationship with anyone" and was "just casually dating."
Jenner was previously linked to Los Angeles Lakers player Jordan Clarkson, One Direction member Harry Styles and singer Nick Jonas.