The synthesis of complex alkyl boronic esters through conjunctive cross‐coupling of vinyl boronic esters with carboxylic acids and aryl iodides is described. The reaction proceeds under mild metallaphotoredox conditions and involves an unprecedented decarboxylative radical addition/cross‐coupling cascade of vinyl boronic esters. Excellent functional‐group tolerance is displayed, and application of a range of carboxylic acids, including secondary α‐amino acids, and aryl iodides provides efficient access to highly functionalized alkyl boronic esters. The decarboxylative conjunctive cross‐coupling was also applied to the synthesis of sedum alkaloids. One‐step to molecular complexity: A decarboxylative conjunctive cross‐coupling of carboxylic acids, vinyl boronic esters, and aryl iodides is described. The reaction proceeds under mild metallaphotoredox conditions and utilizes readily available feedstock materials, including secondary α‐amino acids, to access highly functionalized benzylic boronic esters in a single step.