Farook, who succeeds R S Gavai, was administered the oath of office by Kerala High Court Chief Justice J Chalameswar at a function in the Raj Bhavan.
An eminent public figure, Farook has also served as Governor in Jharkhand, Union Minister and Indian Ambassador in Saudi Arabia.
He served as Puducherry Chief Minister thrice -- the first from April 9, 1967 to March 6, 1968, then from March 17, 1969 to January 3, 1974 and from 1985 to 1990.
74-year-old Farook is the 19th Governor of the state since its formation in 1956. Chief Minister Oommen Chandy, ministers, leaders of various political parties and senior officials were present at the swearing-in ceremony.