In Chennai, the fast was observed at several locations, while the party workers did so in various places including Tiruchirapalli, Cuddalore, Salem, Coimbatore and Kanchipuram.
The film fraternity also rallied behind the AIADMK supremo, shutting down all activities for the day.
Police said no untoward incident had been reported so far in the state, which saw sporadic violence like stone pelting and torching of vehicles in the aftermath of the Bangalore special court's verdict on Saturday, sentencing Jayalalithaa to four years simple imprisonment in the wealth case.
Silent rallies were taken out today in several towns like Kinathukadavu by AIADMK workers. Protesters at all venues hailed Jayalalithaa as the "people's Chief Minister" and raised slogans saying she would eventually emerge triumphant.
The protesters sported black badges and cloths over their mouths. In Tiruchirapalli, Karur and Madurai, sections of traders downed shutters.
Special prayers were held in scores of temples, including the "Rockfort" Lord Ganesha temple in Tiruchirapalli. Prayers were also organised in churches.
A Madurai report said a 17-year-old school student, who was battling for life at a government hospital there after attempting self-immolation, succumbed to burns today.
M Nagalakshmi from Ezhumalai took the extreme step when her family members were away, reportedly upset over Jayalalithaa's jail term. She suffered 80 per cent burns.
Most shops, hotels and theatres in Madurai and surrounding areas remained closed and some private buses were off the roads.
Officials said 80 per cent of the buses were operated in the city while some mofussil buses were also withdrawn.
In Dindigul district, the main state vegetable market at Oddanchattiram was closed, most shops downed shutters and the usually bustling temple town of Palani wore a deserted look. Similar was the case in Kodaikanal.
Fishermen from Rameswaram and neighbouring areas boycotted fishing indefinitely from today, while in Nagapattinam shops remained closed. However, autorickshaws and buses plied and educational institutions also functioned in most places.
In Tiruvarur, constituency of DMK Chief M Karunanidhi, shops downed shutters. Officials said most shops in the district were closed. In Virudhachalam advocates boycotted courts, demanding the release of the former Chief Minister. Shops in several places in Villipuram district also remained closed.