We propose extending the search for dark matter (DM) by considering muon spin targets. An ultralight DM background may apply an oscillating torque to muon spins, resulting in novel precession trajectories. A time-resolved analysis of muon precession data from the upcoming Fermilab and J-PARC g-2 experiments and future frozen spin EDM measurements are sensitive to this signal, and immediate constraints may also be placed using existing g-2 measurements. In addition, some DM candidates alter precession primarily through a shifted precession frequency, i.e. they provide an apparent contribution to the muon magnetic dipole moment which depends on the local DM density. We find that the current muon g-2 anomaly can be explained by pseudoscalar DM which induces an oscillating electric dipole moment for the muon. This explanation may be verified with a time-resolved analysis.
