  The lambda deformation of the pure spinor formalism of the superstring in the
$AdS_{5}\times S^{5}$ background is introduced. It is shown that the
deformation preserves the integrability as well as the one-loop conformal
invariance of its parent theory. It is also shown that the effective action
takes the standard form of the Berkovits-Howe action functional, allowing to
calculate the deformed background supergeometry in a straightforward way. The
background fields coincide with those of the lambda model of the Green-Schwarz
formalism, hence satisfying the same set of supergravity equations of motion.
