Annihilation of dark matter can result in the production of stable Standard Model particles including electrons and positrons that , in the presence of magnetic fields , lose energy via synchrotron radiation , observable as radio emission . Galaxy clusters are excellent targets to search for or to constrain the rate of dark matter annihilation , as they are both massive and dark matter dominated . In this study , we place limits on dark matter annihilation in a sample of nearby clusters using upper limits on the diffuse radio emission , low levels of observed diffuse emission , or detections of radio mini-haloes . We find that the strongest limits on the annihilation cross section are better than limits derived from the non-detection of clusters in the gamma-ray band by a factor of \sim 3 or more when the same annihilation channel and subtructure model , but different best-case clusters , are compared . The limits on the cross section depend on the assumed amount of substructure , varying by as much as 2 orders of magnitude for increasingly optimistic substructure models as compared to a smooth NFW profile . In our most optimistic case , using the results of the Phoenix Project ( ) , we find that the derived limits reach below the thermal relic cross section of 3 \times 10 ^ { -26 } cm ^ { 3 } s ^ { -1 } for dark matter masses as large as 400 GeV , for the b \overline { b } annihilation channel . We discuss uncertainties due to the limited available data on the magnetic field structure of individual clusters . We also report the discovery of diffuse radio emission from the central 30 - 40 kpc regions of the groups M49 and NGC4636 .