To study problems with the Kipriyanov singular differential operator \(\Delta _{B_{-\gamma }}\) with a negative parameter \(-\gamma \in (-1,0)\) , an integral transformation is introduced in the work, based on the solution \(u= \mathbb {J}_\mu \) of the singular Bessel equation \(B_{-\gamma }u{+}u=0\) . This solution is expressed through a Bessel function of the first kind with a positive parameter \(\mu =\frac{\gamma {+}1}{2}\) . An even, odd and complete FBK transform (Fourier—Bessel—Kipriyanov—Katrakhov transform) and a class of singular \(\mathbb {K}\) -pseudodifferential operators are constructed. Theorems on the order and commutator of singular \(\mathbb {K}\) -pseudodifferential operators are obtained.