The photoredox-catalysed Giese-type reaction has emerged as a useful and powerful platform for radical-based transformations. Herein, a novel protocol for the preparation of N-alkylphthalimides has been successfully developed via the reactions of N-vinylphthalimides with radicals using alkyl silicates or Hantzsch esters as the radical precursors. According to the result of deuteration experiments, a mechanism involving a radical addition/SET reduction/protonation process has been proposed. The synthetic application of N-alkylphthalimide has also been demonstrated by deprotecting the phthalimido group using the Ing–Manske procedure.