The legend related to the worship of Lord Ganesha by Lord Shiva is mentioned in the Puranic texts. In the Treta Yuga, there was a prominent sage named Gritsamada. One day the sage had a cough and a child emerged from it. The child named Tripurasura grew up rapidly and intended to conquer the three lokas or worlds. He also desired to defeat Lord Indra. Sage Gritsamada wanted to change his mind and thus asked Tripurasura to worship and praise Lord Ganesha. Hence he began to meditate on the elephant headed deity. Lord Ganesha became pleased by the devotion of Tripurasura and blessed. The deity told him to ask for a boon. Tripurasura requested for three separate forts made of gold, silver and iron respectively. Thus Ganesha presented him with three forts (Tripura); the golden fort was constructed in heaven, the silver fort located in the sky and the iron fort was on the earth. The Lord also announced that only Lord Shiva would be able to defeat the demon Tripurasura with one arrow and destroy the three forts.

Tripurasura became arrogant after receiving the boon from Lord Ganesha and started to create havoc in the Universe. He defeated all the gods in the heaven and all the kings on the earth. The demon had 2 sons. He gave the kingdom of Lord Vishnu to one of his sons and the kingdom of Lord Bramha to the other son.

Then Sage Narada told all the gods and devas to worship and pray to Lord Ganesha who appeared before all the gods. The deity said that only Lord Shiva can annihilate Tripurasura and destroy the three forts. Afterwards Lord Ganesha took the disguise of a Brahmana (Brahmin) and went to visit Tripurasura. The Brahmana told the demon that he was master of sixty four arts. Tripurasura asked the Brahmana to display his arts and if he was impressed, the demon would grant him a boon.

Lord Ganesha then said that he would present him with 3 aircrafts which would take Tripurasura to anywhere in the world. Only Lord Shiva would be able to destroy them. The demon became immensely pleased with this and asked the Brahmana (Ganesha) to request for any gift in return. The Brahmana desired to have the Chintamani which was possessed by Shiva himself. When Tripurasura went to Shiva or Maheshwara to ask for the Chintamani idol, Lord Shiva refused. This resulted in a war between Tripurasura and Shiva. Shiva prayed and worshipped Lord Ganesha and went on a chariot that was built by Lord Vishwakarma, the architect of the gods. Prithvi served as the chariot while the sun and the moon became the wheels. Lord Brahma became the charioteer. Vishwakarma also made the bow and arrow of Lord Shiva. Meru became the bow and Lord Vishnu became the arrow.

After a fierce battle, Shiva destroyed the three forts and the three aircrafts with a single arrow. When Lord Shiva released the divine arrow, lighting emitted from it. Tripurasura became unconscious by the intense light of the arrow and the soul (atma) of the demon emerged of his body in the form of Jyoti. It then entered Lord Shiva.

Another version of the legend states that the Maha Ganapati form of Lord Ganesha was worshipped by Lord Shiva to slay the demon. Tripurasura was a staunch devotee of Lord Ganesha and performed deep meditation on the deity. He was granted a boon from the elephant-headed deity that no one would be able to kill him except Lord Shiva, the Destroyer of the Universe. Eventually Tripurasura became arrogant with his newly found power and started to create disturbance in heaven and on earth.

Later the demon went to Mount Kailash and attempted to abduct Goddess Parvati, the consort of Shiva. Tripurasura thought that he controlled Kailash and it would not be difficult for him to kidnap the goddess. However, Goddess Parvati became very terrified when she realised that Tripurasura was coming to capture her. She immediately went to Himavan, the Lord of Mountains, and informed him about her condition.

Lord Himavan hid Goddess Parvati inside a cave and thus Tripurasura failed to capture the goddess. But the demon managed to seize an image of Lord Ganesha and carried it with him. While the demon was on his way, he discovered that several worshippers of Ganesha were following him. Then all of a sudden the idol of the deity vanished from his hands as well as all the worshippers. Tripurasura realized that this was not a good sign and returned to his forts (Tripura).

Meanwhile, Lord Shiva became much concerned about the evil activities of the dastardly demon. The sage Narada advised Lord Shiva to worship Lord Ganesha. After receiving the blessings of Lord Maha Ganapati, Shiva attacked Tripurasura and successfully vanquished the demon and destroyed his three forts.

There is another version of the legend that states that Tripurasura referred to three asuras or demons named Viryavana, Tarakaksha and Vidyunmali. They were the sons of Tarakasura. The three demons performed long tapas on Lord Brahma. The three demons meditated standing on one leg for almost one hundred years. Later they continued their meditation for another thousand years and consumed only air. Brahma became pleased with their tapas and blessed them with three forts (Tripura) made of gold, silver and iron. Each of the forts was as big as a city and included many palaces and vimanas (aircrafts).

Later the 3 asuras started to create mayhem in heaven and earth. After one thousand years all the three forts merged together and became a single gigantic fort. Then Lord Shiva praised and adored his son Ganesha to seek help in slaughtering the three Tripurasura demons. Ganesha blessed Shiva and told him the way to defeat the asuras. Lord Shiva installed the Pasupata, a celestial weapon, in his arrow and shot at Tripura. It destroyed the fort and burned Tripura.