Kendall Jenner and Blake Griffin have decided to become an official couple.

The 'Keeping Up With the Kardashians' star has been dating the 28-year-old basketball player for two months but, although it was believed their hook ups were nothing serious, the pair have reportedly decided to make things more serious.

A source told UsMagazine.com: ''They're legit. They're a full-on couple.

''Kendall has been going to a lot of his games and they have been enjoying time at home when Blake is in town. They're good.''

The 21-year-old model's new relationship status comes just over a month since it was claimed she was enjoying ''playing the field'' by going on dates with Blake while still talking to her ex-boyfriend rapper A$AP Rocky, who she dated briefly last year.

An insider said at the time: ''Kendall and Blake have been hanging out quite a bit and are having a good time. They met in passing a few times and hit it off.

''She's still talking to Rocky as well. But he isn't the type to settle down or be a good boyfriend, so she's playing the field too. She's seeing Blake romantically. It's nothing serious. She has been in LA a lot lately, and is having fun.

''Work will soon take over her life again, so who knows what will happen will Blake then. She is having fun right now and that's all that matters to her. She takes her career very seriously and that's her number one priority right now.

''Kendall is keeping her options open. She's still dating A$AP Rocky as well, but she and Blake are hanging out, and there's potential there.''

However, this isn't the first time Kendall has decided to make a relationship more official as she previously agreed to get more serious with the 28-year-old rapper.

A source said earlier this year: ''They're definitely still hanging out and are progressively getting more serious.''