A number of festivals are celebrated in the temple, some for a few days and others lasting for just a day. To mark the sun's turning northwards, the Utharaayanam festival is celebrated for ten days in the month of January. The Vasanthautsavam festival in the months of April-May is observed to commemorate Kamadhana, the burning of Man-matha, the personification of desires. This festival also lasts for ten days. The quarrel between the Lord and Goddess and Saint Sundarar's efforts to reconcile their differences is  the celebration of the Thiruvoodal  festival.

Then there is Maha Sivarathri, occurring in February-March. This is a very important, spiritually significant festival that re-enacts the story of Brahma, Vishnu and all other deities paying homage to the column of fire after the humbling of the pride of Brahma and Vishnu. At their request, Lord Arunachala, out of compassion takes the form of lings. On the previous day itself a solemn atmosphere pervades the whole town and the temple.  Tiruvannamalai is the place  where Saivism began and flourished,  Maha Sivarathri has a special significance. The oldest festival of South India which is also the most elaborate and most important. 

Karthigaideepam: This festival falls in the Tamil month of Karthigai  when the star Krithika is on the ascendant and usually occurs on a full moon day. In  Karnarpadu, the poet  in one of the stanzas, describes hoe in the Tamil month of Karthikai during the time of the Krithika star, the lamps lit by the people blossomed on earth,  bringing rain in its wake. In another Tamil work, the Kalavazhi Narpadu dating  back to  the third Sangam period (after 1000 B.C) the poet says, "in the battle the blood oozing out from the dead soldiers' bodies is like the red coloured  flame of the lamps lit during Karthikai deepam  festival". In another Sangam work,  Pazhamozhi,  in stanzas ending in  proverbs,one stanza ends with this phrase, "like the beacon on the Hill." This is a clear reference to the beacon lit on the holy Hill of Arunachala.  Thedeepam festival is not confined to the temple, but involves the whole town. Once a small village, Tiruvannamalai had now grown into a small city. Yet the charm and beauty of the deepam festival will remain the same as it  was hundreds of years ago. The deepam burns for seven, nine, eleven or thirteen days and at about six every evening it flares up and burns through out the night. The deepam is visible for miles around. There is a strange fascination about it. To walk around Arunachala slowly with our attention fixed on the light, without thoughts is a unique experience.