The influence of processing on the micellarization and potential bioavailability of carotenoids from spinach has been previously investigated; however, few studies have looked at the effects of processing on β‐carotene (BC) isomer micellarization. Spinach is often cooked by boiling prior to consumption. The aims of the present study were, first, to investigate the effects of domestic cooking (by boiling) on the isomeric profile of BC in spinach and, second, to assess the effects of cooking on the micellarization of BC isomers. Raw and cooked spinach were homogenized and subjected to an in vitro digestion procedure. The micelle fraction was isolated by ultracentrifugation. Carotenoids were extracted, saponified and analyzed by HPLC. All‐trans BC was the predominant BC isomer in raw and cooked spinach. Following cooking, the percentage contribution of 9‐cis to total BC was significantly (P<0.001) increased and the % contribution of all‐trans BC to total BC was significantly reduced (P<0.001). Micellarization of BC isomers ranged from ca. 20.3 to 60.9 %. Although cis BC isomers in both raw and cooked spinach were more efficiently micellarized when compared with the all‐trans isomer, this trend was not significant. Cooking increased BC isomer micellarization, however this increase was not significant. Our findings indicate that cooking spinach alters the isomeric profile of BC, however, efficiency of micellarization is not significantly affected. This work is funded by Science Foundation Ireland.