Māri originated as an ancient village goddess related to fertility and rain. In Tamil, māri means rain. This goddess was a local deity, connected to a specific location, close to a specific tree, a rock or a special spot, mostly in rural areas.

Another theory regarding origin of the name arises from the fact that mari in Tamil also means change. Thus, the name Maria Amman would mean goddess who has changed. According to some sources, Mariamman is the same as Renuka or YellammaMāri is usually portrayed as a beautiful young woman with a red-hued face, wearing a red dress. Sometimes she is portrayed with many arms, representing her many powers, but in most representations she has only two or four. Her hands may display some mudra and her usual attributes are the trident or spear and the bowl, which are derived from stories told about her.Mariamman was the smallpox goddess before this disease was eradicated. Now she cures all so-called heat-based diseases like pox and rashes. During the summer months in South India (March to June), people walk miles carrying pots of water mixed with turmeric and neem leaves to ward off illnesses like the measles and chicken pox. In this form, goddess Māri is very similar to Sitala Devi, her counterpart in North India and the orisha Babalu Aye of the Yoruba tradition.People also pray to Mariamman for progeny, a good spouse, etc. The most favoured offering is "pongal", a mix of rice and green gram, cooked mostly in the temple complex, or shrine itself, in terracotta pots using firewood.

Some festivals in honor of goddess Māri involve processions carrying lights. In the night, the devotees carry oil lamps in procession, which is a beautiful sight.Most Mariamman temples are humble shrines in villages, where non-Brahmins act as priest using non-agamic rituals. In many rural shrines, the goddess has no form and is represented by a granite stone with a sharp tip, like a spear head. This stone is often adorned with garlands made of limes and with red flowers. These shrines often have an anthill that could be the resting place of a cobra. Milk and eggs are offered to propitiate the snake.

Some temples have also attained enough popularity that Brahmins do officiate at them. For example, at the Samayapuram temple near the shore of river Cauvery, rich agamic traditions are followed and all rituals are performed by Gurukkal of Brahmins.

At Punainallur, near Thanjavur (Tanjore), there is another famous Māri temple. The history says that once Goddess Mariamman appeared to the King Venkoji Maharaja Chatrapati (1676 - 1688) of Tanjore, in his dream and told him that she was in a forest of Punna trees at a distance of about 3 miles from Tanjore. The King rushed to the spot and recovered an idol from the jungle. Under the king's orders a temple was constructed, the idol installed and the place was called Punnainallur. Hence the deity of this temple is known as Punnainallur Mariamman. Mud replicas of different parts of the human body are placed in the temple as offerings by devotees pleading for cure. It is said that the daughter of Tulaja Raja (1729-35) of Tanjore, who lost her eyesight due to illness, regained it after worshiping at this temple.

Other important temples of Mariamman in Tamil Nadu are in the towns of Anbil, Narthamalai,Thiruverkadu, Salem, Virudhunagar and Sivakasi.

Another famous Mariamman temple is situated in the state of Karnataka, in the town of Kaup, 7 km from the famous temple town of Udipi.Mariamman is the sister of Lord Vishnu (Sriranganathar) and called Mahamaya.

The Samayapuram Mariamman is also worshipped on the first day of the Tamil month of Vaikasi by the Iyengar/Srivaishna Brahmins of Srirangam. They claim that she is the sister of Lord Renganath (a form of Vishnu) of Srirangam. This is the second temple in Tamil Nadu, following Palani, regarding income.

Another version suggests that she is the mother of Parasurama, Renukadevi who is appeased for rains. There are many Mariamman Temples in locations outside of India, such as Sri Lanka, Malaysia, Singapore, Thailand, Fiji, Vietnam and South Africa, resulting from the Tamil diaspora. Some of the notable temples include the Sri Mariamman temple in Singapore, a Mariamman temple in Pretoria, South Africa, as well as one in Medan, Indonesia.

Mariamman is actually the goddess Adhi Parashakti, the great mother. She is the one who has created the whole universe. If we joined all the goddesses, they form form mighty goddess who is actually Mariamman or Karumariamman. She is said to have created Brahma, Vishnu and Shiva. She often sit in her assembly with Maha Kali (not Shiva consort), Maha lakshimi (not Vishnu consort) and Maha sarawati (not brahma consort). She is the goddess who rescue you from danger without caring about the consequences about her arrival on earth as she is the ultimate energy and earth won't be able to resist her arrival as she dance in a furious manner liberating all her energy and causin natural calamities. She can be calm as a mother and angry and dangerous as mother kali.