We present a measurement of the effective weak mixing angle parameter sin2θℓeff, in pp¯→Z/γ∗→μ+μ− events at a center of mass energy of 1.96 TeV, collected by the D0 detector at the Fermilab Tevatron Collider and corresponding to 8.6 fb−1 of integrated luminosity. The measured value of sin2θℓeff[μμ]=0.23016±0.00064 is further combined with the result from the D0 measurement in pp¯→Z/γ∗→e+e− events, resulting in sin2θℓeff[comb.]=0.23095±0.00040. This combined result is the most precise measurement from a single experiment at a hadron collider and is the most precise determination using the coupling of the Z/γ∗ to light quarks.