What was the outcome of the referendum that followed the Sikkim assembly's request for full integration with India?

The referendum approved integration with India.

Answer: The referendum approved integration with India.
The hurriedly organized referendum put a stamp of popular approval on the assembly's request for full integration with India.

At the time of Independence, Sikkim was a ‘protectorate’ of India. It meant that while it was not a part of India, it was also not a fully sovereign country. Sikkim’s defence and foreign relations were looked after by India, while the power of internal administration was with the Chogyal, Sikkim’s monarch. This arrangement ran into difficulty as the Chogyal was unable to deal with the democratic aspirations of the people. An overwhelming majority of Sikkim’s population was Nepali. But the Chogyal was seen as perpetuating the rule of a small elite from the minority Lepcha-Bhutia community. The anti-Chogyal leaders of both the communities sought and got support from the Government of India. The first democratic elections to Sikkim assembly in 1974 were swept by Sikkim Congress which stood for greater integration with India. The assembly first sought the status of ‘associate state’ and then in April 1975 passed a resolution asking for full integration with India. This was followed by a hurriedly organised referendum that put a stamp of popular approval on the assembly’s request. The Indian Parliament accepted this request immediately and Sikkim became the 22nd State of the Indian union. Chogyal did not accept this merger and his supporters accused the Government of India of foul play and use of force. Yet the merger enjoyed popular support and did not become a divisive issue in Sikkim’s politics.