She took the sudden decision owing to her 5-year-old pet dog Pebble's ill health.
Tamannaah said in a statement: "I am as big an animal lover as I am a foodie, so giving up the non-vegetarian lifestyle has always been very challenging. However, last month I made a conscious decision since Pebbles got really unwell and suffered a severe paralysis attack.
"He is not just a pet, but a family member and I'm very attached to him. Seeing him go through that discomfort, I vowed to give up something I loved so that he could recoup. It was a conscious sacrifice and I hope I had gone green years ago."
The actress says it was hard to quit non-vegetarian food.
"My upbringing was in a typical Sindhi meat-loving household and I won't say that I don't crave it, but it's all about the will power. It is very important what you eat as that is what you are," she said.
With this, Tamannaah joins Bollywood's bandwagon of advocates for vegetarianism.
On the professional front, Tamannaah is currently working on the Telugu remake of Queen, Sye Raa Narasimha Reddy, Kanne Kalaimanne and F2 Fun and Frustrating.
Images: Tamannaah on Instagram