In the Newar community of Nepal, Ganesh Chaturthi is celebrated as Chatha Puja, observed on the fourth day of the bright fortnight (Shukla Chaturthi) in the month of Bhadra. This festival is dedicated to Lord Ganesh, also known as Vinayaka, revered as the remover of obstacles and the bestower of success (Siddhi Data). Chatha Puja is both a spiritual and cultural occasion, blending Newar Hindu and Vajrayana Buddhist traditions, where Ganesh is venerated as a guardian of new beginnings.

A distinctive aspect of this celebration is the avoidance of moon sighting, rooted in an ancient legend. According to the story, Lord Ganesh once cursed the Moon God (Chandradev) for mocking his appearance, declaring that anyone who looked at the moon on this day would face false accusations and dishonor. To this day, Newars perform the evening puja after sunset, deliberately avoiding the moon to honor the tradition and the deity.

During Chatha Puja, devotees engage in ritualistic worship at home and at local Ganesh shrines, including renowned sites like Chwasa Ganesh across the Kathmandu Valley. Offerings are carefully prepared and include ginger, pear beans, soya beans, cucumber, roasted corn, groundnuts, wheat, and sacred sweets. Traditional foods like Samaybaji are also part of the ritual. Unlike other regions where Ganesh Chaturthi is celebrated with grand idol immersions, the Newar observance emphasizes home-based rituals, family gatherings, and spiritual reflection, focusing on seeking blessings for protection, prosperity, and success.

Chatha Puja is therefore not only a devotional festival but also a celebration of Newar cultural heritage, preserving centuries-old traditions and beliefs, including the unique observance of avoiding the moon, which adds a distinctive spiritual and cultural significance to the occasion.