The day begins with an early morning bath, adorning of new clothes and offering prayers at home.

On the day of Thiruvonam conical figures in various forms are prepared from sticky clay and are painted red. These are decorated with a paste made of rice flour and water and are placed in the front court yard and other important places in the house. Elaborate prayer ceremonies and poojas are also performed on this day. A senior member of the house plays the role of the priest and conducts the rituals. He wakes up early and prepares ada- (rice flour and palm sugar) for Nivedyam (offerings to God). Lamps are lit up in front of the idols and all members of the house join in for the ceremonies. The priest offers ada, flowers and water in the names of the gods. As Onam is also a harvest festival, people thank God for the bountiful harvest and pray for the blessings in the coming year. A quaint custom follows after this, where male members make loud and rhythmic shouts of joy. The tradition is called, Aarppu Vilikkal. This signals the arrival of Thiruvonam.

There is also a tradition of distributing new clothes on Onam. In Tharawaads the Kaarnavar, gives new clothes as gifts, called Onappudava, to all family members and servants.