This study is concerned with the optimal time rates of weak solutions for the 2D magneto-micropolar equations with only micro-rotational dissipation and magnetic diffusion. Due to some new observations, we obtain the optimal time decay rates of weak solutions $\|\nabla u(t)\|_{L^2}+\|\nabla w(t)\|_{L^2}\le C(1+t)^{-2}$ and $ \|\nabla b(t)\|_{L^{p}}\le C(1+t)^{-\frac12-(1-\frac1p)}$ with $p\in[2,\infty)$.