Appelman was born and raised in Palo Alto, California, and attended high school there.

[3] Appelman played many sports in high school, including track and field, wrestling, and competitive martial arts.

[3][better source needed] He would then go on to act in regional theatre in such productions as Hamlet, Timon of Athens, King Lear and A Midsummer Night's Dream.

[4][better source needed] In season 15 of Law & Order: Special Victims Unit, Appelman guest starred as Officer Jimmy Hamilton in two episodes.

[4][better source needed] On August 21, 2015, it was announced that Appelman had been made a series regular on Sleepy Hollow.