Their sudden new romance has come under the spotlight in recent weeks, but the pair looked blissfully happy in the photo shared via Snapchat.
In the snap, Rob is dressed in black, wearing a Los Angeles Dodgers baseball cap, while model girlfriend Blac attempts to pull him in for a kiss.
Since going public with his romance with Blac, Rob has been seen out in public more often.
Rob, who is known to struggle with his weight, was recently diagnosed with diabetes, and compared to his mega famous family, he has shunned the limelight for several years.
However, it has been reported that he has been increasing his fitness routine since his romance with Blac .A source told E! News that Rob has been "taking better care of himself since his health scare", with Blac helping him.
Earlier this week, Rob also posted a message on Instagram, which read: "Progress = Happiness."
Rob's Snapchat comes as his sister Khloe Kardashian took to Instagram to say she missed him. Sharing an old photo of Rob kissing her on the cheek, she said: "It's simple..... I miss you."
Reports claimed that the siblings hit a rocky patch when Rob began dating Blac this year, as Blac is the ex-fiance of Kylie Jenner's now boyfriend Tyga.
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