The first organocatalytic diastereo- and enantioselective domino Michael/aldol reaction of 3-halogeno-1,2-diones to α,β-unsaturated aldehydes has been achieved. This transformation tolerates a large variety of electronically different substituents on both reactive partners and allows the synthesis of challenging cyclopentanone derivatives with four contiguous stereogenic centers in excellent diastereoselectivities (>20:1 dr) as well as good yields (69–97%), and enantioselectivities (up to 94% ee).