The work presents the late-time cosmology in $f(Q, T)$ gravity, where dark energy is strictly geometric. We assume that the universe is governed by pressure-less matter that produces a scale factor $a(t)$. We begin by using a well-motivated gravity model $f(Q, T)= m Q^{n} + b T$, where m,n, and b are model parameters. Also, constraints on the model parameters from the revised 57 points of Hubble data sets and 580 points of union 2.1 compilation supernovae data sets are placed to investigate the model's cosmological viability. We have also thoroughly examined the existence of dark energy with the assistance of {s-r}, {q-r} diagnostic analysis. The present study makes it clear that gravity $f(Q, T)$ can be promising in resolving the existing cosmic acceleration and, thus, an acceptable solution to the issue of dark energy.