The couple welcomed baby True Thompson back in April.
The 33-year-old donned a black Cleveland T-shirt and tight ripped jeans for the occasion. She wore her long blonde hair down and kept her makeup light.
The Cleveland home game ended in a loss for Thompson's team, giving the Golden State Warriors a 3-0 series lead.
ET spoke to Sonny Johnson, who took a picture of Kardashian with his wife, Sianez, and said the reality star was all smiles during their brief meeting and told his wife it was nice to meet her. Johnson -- who's the boys basketball coach at Garfield Heights High School in Cleveland, Ohio --says Kardashian appeared more than happy to be at the game to cheer on her man.
ET also spoke to Yasmeen Alston, who snapped a picture with Kardashian alongside her friend, Jar'la Evans. Alston tells ET, "Khloe was great. Very personable. She waved and blew kisses during the game and stopped for a photo-op afterwards."
Despite the allegations, Kardashian has been spending time with Thompson in Cleveland since True's birth. Her mom, Kris Jenner, exclusively told ET's Leanne Aguilera that she expects her eldest to return to L.A. soon, though.
"She's great! Yeah! Really, really, really great. [Khloe is] loving being a mom," Jenner said last week. "She'll be back really soon."
Back in May, a source told ET that Kardashian is "planning on being in Cleveland for another month."
"She’s built a nice, quiet life for herself in Cleveland, which is exactly what she wants right now. She’s really enjoying this quality time with her daughter and Tristan -- without all the distractions that come with being in L.A. surrounded by so many other people," the source explained. "She’s doing really well and, of course, is very hands-on with True."
Some people have been criticizing Kardashian's response to the cheating rumors. The reality star took to Twitter earlier this month to stand up to the trolls.
"Babe that’s not wisdom at all because you’re assuming you know who I’m talking about and you’re assuming you know my feelings," Kardashian tweeted in response to a fan's tweet. "Assuming anything is anything but wisdom."
Here's more on Kardashian's response to Thompson's cheating scandal:
Khloe Kardashian Shares Her Thoughts on Kanye West's New Album That References Tristan Thompson Scandal