As the country's anthem played, participants held up crimson, blue and white coloured cardboard for 10 minutes on an open ground in Kathmandu's city centre to form the national flag.
Cries of "Nepal!" rang out as participants threw the cardboard pieces in the air to celebrate after the attempt.
Nepal's flag is the world's only one which is not a quadrilateral. Instead it is comprised of two triangles.
Nepal is in the process of drafting a new constitution, a key step in a stalled peace process begun after the end of a ten-year civil war in 2006. Leaders have promised an inclusive constitution and federalism, ending gender and caste-based discrimination.
The current record for the world's largest human national flag was set in February 2014 when 28,957 people gathered in Lahore, Pakistan, to create a Pakistani flag, according to Guinness World Records.