Kylie Jenner's office building served as the backdrop for a police apprehension ... because cops arrested a guy out front, and they drew their guns!!!

Photogs camped outside Kylie's office hoping for a glimpse of the reality TV star got more than they bargained for Tuesday when a police bust played out right in front of them.

Check out the gallery ... Los Angeles County Sheriff's deputies rolled up on a guy on the sidewalk outside Kylie's office and arrested him with their pistols drawn.

Law enforcement sources tell TMZ ... the arrest was unrelated to Kylie or her office.

We're told the bust related to an alleged robbery of an Albertsons supermarket down the street from Kylie's office complex.

Cops believe the same suspect may have committed another crime earlier in the day before getting released from jail and allegedly hitting the Albertsons.

Kris Jenner's also got a tie-in here ... her office is nearby too.