The state assembly cleared the amended Gujarat Animal Preservation Act of 1954 on the last day of the Budget Session to make killing of cows punishable with life imprisonment.
Moreover, those found guilty of transporting beef will also be jailed for 10 years.
The penalty for either act has also been doubled from 50 000 Indian rupees ($770) to 100 000 rupees.
The new law came into effect on Saturday.
A cow is considered as a holy animal by majority Hindus in India.
Killing of cows is illegal in many Indian states. — Xinhua.