AbstractCombining the regioselective room temperature/ambient pressure hydroformylation and a modification of the Doebner–Knoevenagel reaction allowed for the development of an efficient, one‐pot procedure for the synthesis of (E)‐α,β‐unsaturated carboxylic acids. The reaction proceeds under mild conditions, tolerates a variety of functional groups and gives (E)‐α,β‐unsaturated carboxylic acids in good yields and with excellent regio‐ and stereocontrol. The practicability of this process has been demonstrated by a short protecting group‐free synthesis of the queen honeybee pheromones 9‐ODA [(E)‐9‐oxodec‐2‐enoic acid] and 9‐HDA [(E)‐9‐hydroxydec‐2‐enoic acid].