National parks are a destination for nature-based tourism (NBT) in both the developed and developing countries. National Park visitors with pro-environmental attitudes may be more likely to support the management's conservation efforts. However, managing and funding national parks and protected areas is a significant challenge, particularly in low-income countries. Visitor entrance fees to national parks are an often-heard option to secure sustainable funding for the management. This study aimed to measure environmental attitude and willingness to pay (WTP) for park entrance fees of international visitors to Langtang National Park in the Nepal Himalayas. The New Ecological Paradigm (NEP) scale was applied to assess environmental attitude, while a contingent valuation survey was carried out to explore WTP. International visitors of the park (n= 476) were surveyed over two years. The survey results suggest that national park visitors exhibited comparatively high pro-environmental attitudes, with a NEP score of 3.72 (5 being the highest score). Visitors were willing to pay a new entrance fee of USD 57.51 (mean) in comparison to the existing fee of USD 30. The willingness to pay a higher entry fee was positively correlated with a pro-environmental attitude and income. The increase in entrance fees could significantly improve the funding of national parks in Nepal and lead to an upgrade of its infrastructures without reducing the overall number of visitors.