One of the most striking traditional customs of the island are the festivals and their rituals.

Festivals in Sifnos are usually held in the afternoon the day before the name day. But there are also festivals that take place on the same day, early in the morning. Believers attend evening prayers and after the breaking of bread everyone eats together at the traditional ‘refectory tables’ (trapezes) reminiscent of the early Christian Agape Meals (Love Feasts). The dinner includes chickpea soup and braised lamb with potatoes or pasta (or cod with cabbage salad if the festival coincides with the Lent fasting period), all cooked in "panostries" (raised fireplaces). Wine and traditional ‘takimi’ music (played by a violin and lute duet) are never absent from the dinner. The tables are set and reset again and again until everyone present has eaten.

Singing and dancing often continues on until morning. The costs of the festival are assumed by the ‘panigiras’ or ‘panigirades’ (if undertaken by a ‘brotherhood’), and include cleaning and whitewashing the church ready for the feast, food, cooking, wine, payment of priests and cantors, musicians, everything. In return, the 'panigiras’ keeps the icon of the saint in their home throughout the following year. On the day of the festival the icon is brought to the church in a special ceremonial procession accompanied by the priest and parishioners. The following year another person takes charge of the icon, and assumes responsibility for the costs of next year’s festival. This custom is so popular that some churches have waiting lists years long.

Festivals are held throughout the year but most of the more popular are those held from autumn to spring, often in remote locations.

The biggest festival of all is that of the patron saint of the island, Panagia Chrysopigi, celebrated on Ascension Day, attended by many people from all over the island and beyond.

In the afternoon of the day before, the miracle icon of Zoodochou Pigis (the Life-Giving Spring) is ‘transported’ from the home of the ‘panigiras’ and the festival procession, with the clergy and the faithful, follows the path to the Holy Church of Agios Georgios in Kamares where the liturgy is held. Then the clergy, with the ‘panigiras’ carrying the icon, board the ferry that each year on this day adds the sacred rock of Chrysopigi to its route from Piraeus. The ship does not carry the believers because disembarkation is potentially dangerous. The crowd of believers, local people and visitors, take the road to Chrissopigi where the arrival of the icon is greeted with great enthusiasm, and the celebrations are honoured by music of the Coast Guard band. Immediately after, the Polyarchieratic Ceremony of the Great Vespers is held. It is followed by the Dinner (Love Feast), the Litany and the Holy Vigil. On Ascension Day itself, the icon is taken by fishing boat to Seralia in Kastrou. From here begins the procession around the island’s main villages. It ends at the Cathedral of Agio Spyridon in Apollonia, where it is handed over to next year’s ‘panigiras’.

Some of the traditional festivals (accompanied by food and Sifnos island music) that are celebrated during the tourist season include:

• In May or June (a moveable feast day): Analypseos or Ascension Day, which celebrates the patron saint of the island, Panagia (Our Lady) Chrysopigi!
• 13 June: Elissaios (Elijah) at the chapel dedicated to him, downhill from Ai Nigia
• 12 July: Feast day of the Taxiarchi (Archangel), celebrated by the church of the same name in Vathi and Ai Silivestro (on the road to Herronisos)
• 17 July (πρωί):Agia Marina at the church in Flambouro
• 19 July: Profitis Elias, celebrated at the Monastery of Profitis Elias t’Apsilou (Prophet Elias ‘the Tall’) in Ai Nigia, and the churches dedicated to the prophet at Troulaki and Kontou.
• 26 July: Agios Panteleimon and Ai Polycarpos in Herronisos
• 14 August: The festival of the Panagia (Our Lady) at Platanissa, Panagia Toso Nero, and Panagia tou Niliou in Poulati. (Because of the multitude of churches that celebrate the Assumption on the 15th of August, the day of the festival may be changed)
• 28 August: Ai Yiannis at Honi, Mavro Chorio, Siderou and Maggana
• 29 August (morning): A small festival celebrating Ai Yiannis at Faros.
• 31 August: Agios Symeon in the church dedicated to him, and the Pantocratora (the Almighty) (on the road to Platy Gialos)
• 5 September: Taxiarchi (Archangel) in Vathi
• 6 September: Agios Sozontos at Ai Sosti
• 7 September: Genethlio tis Theotokou (the birthday of the Holy Mother) at the Holy Monastery of Vrysis (Vrysiani)
• 13 September: Timios Stavros (the Holy Cross) at Stavros in Faros and Honi (on the way to Herronisos)
• 15 September: Agios Nikitas, at Seladi