In this paper, we consider the dual Toeplitz operators on the orthogonal complement of the Fock–Sobolev space and characterize their boundedness and compactness. It turns out that the dual Toeplitz operator
S
f
is bounded if and only if
f
∈
L
∞
, and
S
f
=
f
∞
. We also obtain that the dual Toeplitz operator with
L
∞
symbol on orthogonal complement of the Fock–Sobolev space is compact if and only if the corresponding symbol is equal to zero almost everywhere.