He joined the second season of Nalaya Iyakunar (a TV competition for short films) to build his portfolio.

[4] Kumar made his feature film directorial debut with Pannaiyarum Padminiyum (2014) starring Vijay Sethupathi.

[6] Though it won critical acclaim and was screened at many international film festivals,[7] it was not successful at the box office.

[10] Arun Kumar joined hands with Vijay Sethupathi for the third time for Sindhubaadh (2019).

[14] Kumar made a documentary called Imaikka Vizhigal in 2020 about the chain snatching epidemic in Tenkasi.