The main Ulsavam is celebrated for ten days in the Malayalam month of Kumbham. Main Prathistha or diety is Sree Ayyappan. Upaprathistas include Sree Ganapathy, Navagrahangal, Sree Brahma Rakshassu, Nagaraja, etc.. Event called Theeyattu starts on 1st of Vrichikam month of Malayalam calendar. It lasts for 40 days. Aarattu is on the 10th day of Uthram in Kumbham month. Also used to have Kalam Paattu on these days.
From November to January, tens of thousands of devotees from Palakkad, Malapuram and Thrissur districts reach Ayyappan Kavu to wear the Ayyappa mudra and to start their pilgrimage to Sabarimala. During this season, a number of Ayyappan Vilakku are also performed in front of the temple. Cherpulassery Ayyappan Kavu is one of the few temples where marriages are performed in the presence of Lord Ayyappa. A traditional temple art called Thiyyattu is also performed at the temple during the 10-day festival season. A Swayambu kshetra and covered with a gold Kavacham. Ilayada Nivedhyam is the specialty of this temple.
The annual festival is observed in Malayalam Kumbham month (February – March). Cherpulassery Ayyappan Kavu festival starts with flag hosting and ends with Arattu on the last day. The annual festival is noted for various rituals including Thiyyattu.
Thousands of people arrive on the day to witness various rituals and festivities. Special poojas are held during the festival days in which thousands of devotees participate. Chendamelam and panchavadyam also form a part of this festival. Parayeduppu and elephant procession provides a visual treat to the devotees.
Traditional performing arts, music and dance are staged during the period. The temple is traditionally decorated with plantain, coconut leaves, flowers, leaves, traditional lamps and lights.