Let $R$ be an Artin algebra and $e\in R$ an idempotent. We study when the recollement ideal $ReR$ induces (left) recollement of Gorenstein defect categories. As a consequence of this phenomenon, concrete triangle-equivalences between Gorenstein defect categories (resp. stable categories of Gorenstein projective modules) of $R$ and $R/ReR$ (resp. $eRe$) are obtained, and reduction conditions for Gorensteinness (resp. CM-freeness) of $R$ and Gorenstein projective conjecture over $R$ are provided. Finally, some applications in the context of triangular matrix algebras are given.