Rams receiver Demarcus Robinson was robbed at gunpoint in Los Angeles on Friday morning ... and cops say they were told the brazen thieves made off with over $100K worth of jewelry.
Law enforcement sources tell TMZ Sports ... officers responded to calls of a robbery outside a Los Angeles area hotel just after midnight.
Cops were told two men approached the 29-year-old football player, pointed firearms at him ... and demanded he hand over his valuables -- which included a pricey watch.
Our sources say Robinson obliged .