Since the late 1980s, he has amassed a number of credits in the film and television industry. He edited the films Cheerleader Camp, Think Big, 3 Ninjas Kick Back, and BASEketball.
He began directing television and film during the 1990s, his credits include Mighty Morphin Power Rangers, The Sentinel, Trouble Bound, Haunted, Columbo, The Division, Surface, Friday Night Lights, Caprica and Trauma.
He was executive producer and house director for the NBC series The Event under his deal with Universal Media Studios during the show's 2010–2011 run.
In 2011, Reiner was chosen to direct the pilot for a David E. Kelley-produced Wonder Woman television series for NBC. The pilot was ultimately not picked up for series.
In 2014, Reiner directed five episodes of the television drama The Affair. The show subsequently won a Golden Globe for Best TV Series, Drama.
Reiner has also worked on the FX TV series Fargo.