Abstract: A full-dimensional global potential energy surface for the KRb + KRb → K₂ + Rb₂ reaction is developed from 20 759 ab initio points calculated using a coupled cluster singles, doubles, and perturbative triples (CCSD(T)) method with effective core potentials, extrapolated to the complete basis set limit. The ab initio points are represented with high fidelity (root-mean-square error of 1.86 cm^–1) using the permutation-invariant polynomial–neural network method, which enforces the permutation invariance of the potential with respect to exchange of identical nuclei. The potential energy surface features two D_2h minima and one C_s minimum connected by the isomerization saddle points. The Rice–Ramsperger–Kassel–Marcus lifetime of the K₂Rb₂ reaction intermediate estimated using the potential energy surface is 227 ns, in reasonable agreement with the latest experimental measurement.