On May 27, 2016, McKenry signed a minor league contract with the [[2016 St. Louis Cardinals season|St. Louis Cardinals]].<ref>{{cite web |url=http://www.mlbtraderumors.com/2016/05/angels-outright-lucas-luetge-blue-jays-sign-lavarnway.html |title=Minor MLB Transactions: 5/27/16 |last=Todd |first=Jeff |work=MLB Trade Rumors |date=May 27, 2016|accessdate=May 28, 2016}}</ref> On July 7, the Cardinals selected McKenry's contract, adding him to their active roster.<ref>{{cite web|url=http://www.cbssports.com/fantasy/baseball/news/cardinals-mike-mckenry-contract-purchased-by-cardinals/ |title=Cardinals' Mike McKenry: Contract purchased by Cardinals |date=July 7, 2016 |accessdate=July 7, 2016}}</ref> He logged two plate appearances for St. Louis before he was designated for assignment on July 19.<ref>{{cite news |last=Timmerman |first=Tom |url=http://www.stltoday.com/sports/baseball/professional/cardinal-beat/peralta-goes-on-dl-with-thumb-strain-hazelbaker-returns/article_8debca38-1b56-5bfe-895d-8c7bbcf549de.html |title=Peralta goes on disabled list; Hazelbaker returns |work=[[St. Louis Post-Dispatch]] |date=July 19, 2016 |accessdate=July 20, 2016}}</ref> He elected free agency on July 22.