Starting off as an intern on Smallville, Miller eventually worked his way up to becoming a staff writer for the series by season Eight. His work on the show eventually lead him to begin working at DC comics where he wrote a few issues of Teen Titans. In late 2009, he would relaunch Batgirl with Stephanie Brown starring as Batgirl. The series was met to much acclaim from fans, but would eventually be cancelled with the launch of The New 52, where Barbara Gordon would regain her mobility, and take on the role of Batgirl once again. Beginning in April 2012, Miller would be at the helm writing Smallville: Season Eleven, a continuation of the TV series in comic form, drawn by frequent Batgirl artist Pere Pérez. The series would first come out in short digital chapters, later being collected into print a few weeks after initial release.