Because consumers integrate components of their habitat through diet over time and space, stable isotope ratios from animal tissues can track spatial variation in baseline values across marine systems. To understand large‐scale geographic patterns in the eastern Pacific ocean, muscle δ13C and δ15N from epi‐mesopelagic squid (n = 404) were collected from 39° S to 53° N and analyzed in relation to hemisphere, latitude, geographic area and current systems. Geographic patterns were controlled for effects of secondary factors such as squid size, species (Dosidicus gigas and Sthenoteuthis oualaniensis), tissue and year of collection. Joint latitudinal variation of δ13C and δ15N was also described for the first time. Both δ13C and δ15N, as well as the standardized difference between them, had distinct patterns by latitude. δ13C was the highest at 22°S and decreased north and south of that latitude, with lower values at mid‐northern latitudes than near the equator. δ15N had the lowest values near the equator and gradually increased towards mid‐latitudes. The standardized difference between δ13C and δ15N was highest (C was higher relative to N) near the equator and declined to mid‐latitudes. Overall, the δ13C and δ15N geographic patterns agreed with previous studies for δ15N from surface NO3−, but not for δ13C in plankton, POM and squid. We suggest that the biochemical processes for carbon and nitrogen are spatially more variable than what has previously been reported because squid isotope ratios varied also among current systems and geographic areas. These geographic patterns in δ13C and δ15N, indicated by consumers such as cephalopods, could improve our understanding about the interaction between the carbon and nitrogen cycle and the heterogeneity in biochemical cycling processes in marine systems.