In September 2011, Alexander filled in as the drummer for My Chemical Romance on their "Honda Civic tour", after touring drummer Michael Pedicone was fired after being caught stealing from the band. Alexander has continued to play with My Chemical Romance into 2012, including their appearances on the Australian Big Day Out tour dates and their final show at Bamboozle Festival. After their last concert, he stayed with the band and also recorded "Fake Your Death" until the band broke up in 2013. He's also contributed to My Chemical Romance members Gerard Way, Ray Toro, and Frank Iero's respective solo projects, after the break-up of the band.