In continuation of studies on Algerian Apiaceous plants, we report the isolation and structural determination of a new furanocoumarin glycoside, carumoside 1 (xanthotoxin-5-O-β-D-glucoside), and the known coumarin xanthotoxin 2 from Carum montanum. Aerial parts were extracted with boiling 70% MeOH, and fractions were isolated via solvent partition and silica gel chromatography. Structural elucidation of carumoside 1 was performed using UV, FABMS, 1H/13C NMR, HMBC, and HSQC experiments, with acid hydrolysis confirming the glucose moiety. Chemotaxonomic analysis shows that the presence of coumarins aligns Carum with Apiaceae family traits, and 5-glucosylated furanocoumarins are a distinctive characteristic of C. montanum, the first endemic species of the genus studied in Algeria.