After making brief appearances in the films Kadhalil Sodhappuvadhu Yeppadi and Pizza (2012), he portrayed a kidnapper in Nalan Kumarasamy's Soodhu Kavvum and a comic villain in Alphonse Putharen's Neram.

Simha's subsequent performance as the Madurai gangster Sethu in Karthik Subbaraj's Jigarthanda (2014) won him critical acclaim and the National Film Award for Best Supporting Actor.

[4] In 2005, he participated in a Coimbatore-based event called Naalaya Natchathiram, where chief guests Sundar C and E. Ramdoss suggested that he should attempt to become an actor in Tamil films.

[4] Simha stated that he received an offer to feature in a TV serial in Chennai and only after making the journey from Coimbatore, did he realise he had been conned.

[4] Simha subsequently finished his degree and came back to Chennai to pursue a career in acting but ended up working in marketing, insurance and business process outsourcing to fulfill his financial needs.

[8] The pair subsequently made a series of short films together, with Subbaraj giving Simha a role in his directorial debut Pizza, too.

[9] Simha then appeared in Soodhu Kavvum (2013) portraying the role of Pagalavan, and played the antagonist in the bilingual Neram,[10] his performances in both films were received well.

[30] He was seen in Amazon Prime Video's Anthology Putham Pudhu Kaalai, where he played the lead role in Karthik Subbaraj's segment titled, Miracle.

In 2022, Bobby Simha play in pivotal role with Vikram in Mahaan directed by Karthik Subbaraj exclusively on Prime Video.