Pamakwikwi eOlympic a2012 muLondon, akaputsa zvakare rekodhi yake yekuAmerica uye akaisa rekodhi yeOlympic nenguva yemasekonzi 56,25 mumakwikwi e100-metre butterfly qualifying heat. Mumakwikwi okupedzisira emamita 100, akahwina menduru yegoridhe ndokuisa rekodhi itsva yenyika nenguva yake ye55.98. Vollmer akakwikwidzawo mumakwikwi e4×200-metre freestyle relay
. Akashambira muchikamu chechipiri nenguva ya1:56.02, sezvo chikwata cheU.S. chakahwina ndarama nenguva ya7:42.92. Mumutambo wake wokupedzisira, 4×100-metre medley relay, Vollmer akakunda imwe ndarama naMissy Franklin, Rebecca Soni naAllison Schmitt. Achishambira netsoka yemabhururu, Vollmer akarekodha nguva yakakamurwa ye55.48, sezvo timu yeU.S. yakaisa rekodhi yenyika itsva nenguva ye3: 52.05, ichivandudza rekodhi yapfuura ye3: 52.19 yakagadzwa neChina muna2009.