"Bachelorette" star Kasey Kahl was arrested Sunday morning in Fresno, CA -- hometown of Kevin Federline -- after cops say he was drunk and disorderly at a nightclub ... TMZ has learned.

Law enforcement sources tell TMZ ... Kahl -- who recently appeared on "Bachelor Pad" -- was allegedly involved in an incident at a place called Club Habanos. So far, it's unclear exactly what Kahl is accused of doing wrong.

Kahl was booked at a nearby police station -- where he took one of the prettiest mug shots we've ever seen and was released a few hours later.

Kahl just finished taping the inaugural season of VH1's upcoming "Relationship Rehab" with former GF Vienna Girardi.

4:25 PM PST: A rep for Kahl tells us, "Kasey and his friends were hanging out outside of the club where police officers allegedly thought they were being too loud.  Kasey, along with a couple friends, were taken to the police station, but were released a couple hours later. No charges were or have been filed against him."

The rep adds, "Kasey was extremely respectful and very cooperative with the police officers despite the situation, even having a good laugh because of his model-esque mugshot. The police officers noted that it was the prettiest mugshot they've ever seen come into their station."