© 2019 SLAC National Accelerator Laboratory. All rights reserved. In the mQ → ∞ limit, the hyperfine splittings in the ground state doubly heavy baryons (QQq) and single heavy antimesons (Q̄q) are related by heavy quark-diquark symmetry (HQDQ) as the light degrees of freedom in both the hadrons are expected to have identical configurations. In this article, working within the framework of nonrelativistic QCD (NRQCD), we study the perturbative and nonperturbative corrections to the HQDQ symmetry hyperfine splitting relation that scale as O (α2s) and Λ2QCD/m2Q respectively. In the extreme heavy quark limit, the perturbative corrections to hyperfine splitting of doubly charm or bottom baryons are a few percent or smaller. The nonperturbative corrections to hyperfine splitting are of order 10% in the case of doubly charm baryons and 1% or smaller in doubly bottom baryons.