Described herein is a practical and convenient approach that enabled radical-mediated conjugate addition of unreactive alkenes to electron-deficient alkenes leading to a broad range of substituted malononitriles. These reactions are believed to proceed by Fe-catalysed hydrogen atom transfer (HAT) onto the alkenes affording carbon-centered radical intermediates with Markovnikov selectivity, followed by the capture of electron-deficient alkenes. We explored this synthesis approach under mild conditions with high efficiency and broad substrate scope and the utility is highlighted by the further synthetic transformations of the obtained substituted malononitriles.