Tala Safwan, who has five million followers on TikTok and some 800,000 on YouTube, drew rage online amid claims a recent video had lesbian undertones.
But Ms Safwan said that had not been her intention.
Police in the strictly conservative kingdom however said the video could harm public morality.
With her short dark hair and expressive face, the young vlogger’s sparkling, upbeat style is aimed at teenagers.
Her videos have catchy, tabloid-like headlines as she discusses TV shows and issues sent in by her followers – mostly about relationships and embarrassing situations.
She sets up pranks and carries out challenges – just like many other successful content creators around the world.
But one of her recent videos has drawn a very different reaction.
In the clip, she’s seen chatting to a female Saudi friend, whom she invites over to her house. Her subsequent remarks have been interpreted by some as being sexually suggestive.
That set off a big campaign against her, with a hashtag trending on Twitter that translates as “Tala offends society”.
She responded by saying she’d been misunderstood and denying there was any lesbian subtext in her comments – a subject that is still publicly taboo in Saudi Arabia.
She said that the clip had been taken out of context from the full video she recorded, in order to cause a scandal.
As the social media pile-on continued, the police in Riyadh announced that they had arrested a local resident “who appeared in a broadcast talking to another woman with sexual content and suggestiveness that could have a negative impact on public morality”.
The police did not name Tala Safwan, but included a clip of the video with her face and that of her friend blurred.
It comes just days after the Saudi media regulator demanded that YouTube remove advertisements that it considers offensive to the country’s Muslim values and principles. The regulator threatened to take legal action if nothing was done.
The announcement followed complaints by Saudi parents that their children were being exposed to inappropriate content in ads broadcast on YouTube.