We report the determination of the Landé gJ factor and Zeeman coefficients for the ground-state of 171Yb+, relevant to microwave quantum frequency standards (QFSs). The gJ factor is obtained by using two independent methods, the multiconfiguration Dirac-Hartree-Fock and multireference configuration-interaction methods, yielding a consistent value of 2.002615(70). The first- and second-order Zeeman coefficients are determined as 14010.78(49)Hz/µT and 31.0869(22)mHz/µT2, respectively, based on the calculated gJ factor. These coefficients enable reduced magnetic-field-induced uncertainties, improving the accuracy of the 171Yb+ microwave QFSs. The results reported in this work also offer potential for improved constraints on variations in fundamental constants through frequency comparisons and advancing trapped-ion quantum computers based on the ground-state hyperfine splitting of 171Yb+. locked icon locked icon Physics Subject Headings (PhySH)Atomic & molecular structureZeeman effect