It is difficult to determine the most watched series on ULLU, as the platform does not release viewership figures for its content. However, some popular web series produced by ULLU include:
- "Charmsukh"
- "Pareeksha"
- "Gandi Baat"
- "X.X.X"
- "Lust Stories"
- "Kavita Bhabhi"
- "Halala"
This list is not exhaustive and may not include all the popular web series produced by ULLU. The popularity of a web series can depend on various factors, such as the quality of the content, the acting, the production values, and the marketing efforts of the platform.