For years, Nepal depended on Indian telecom companies, such as Bharti Airtel and Tata Communications Ltd, for access to the worldwide web, which Nepali officials said made connections vulnerable to network failures.
Nepal Telecom and China Telecom Global launched their services after they wrapped up the laying of optical fiber cables between Kerung in China and Rasuwagadi in Nepal, about 50 km (30 miles) north of Kathmandu, the companies said.
"This will give us an alternative to India for cyber connectivity and ensure uninterrupted connections," Pratibha Vaidya, a Nepal Telecom spokeswoman, told Reuters.
"Consumers can now look forward to a reliable service."
More than 60 percent of Nepal's 28 million people had access to the internet last year, up from just 19 percent in 2012.
In 2016, Beijing agreed to allow Nepal to use its ports to trade goods with third countries, ending Kathmandu's sole dependence on India for overland trade.
Nepal last year joined the Belt and Road Initiative, which is China's effort to develop a modern "Silk Road" connecting Asia with Europe, Middle East and Africa by road, railway, sea and air.
As part of the initiative, Nepali officials say they are in talks with Beijing over the extension of the Chinese railway network into Nepal from Tibet.