TikTok, owned by Chinese tech company ByteDance, has already been either partially or completely banned by other countries, with many citing security concerns.
More than 1600 TikTok-related cyber crime cases have been registered over the last four years in Nepal, according to local media reports.
Nepal's Minister for Communications and Information Technology Rekha Sharma said the decision to ban TikTok had been made at a cabinet meeting on Monday.
"Colleagues are working on closing it technically," Sharma told Reuters.
Nepal Telecom Authority Chair Purushottam Khanal said that internet service providers have been asked to close the app.
"Some have already closed while others are doing it later today," Khanal told Reuters.
TikTok did not immediately respond to a request for comment on the matter.
It has previously said such bans are "misguided" and that they are based on "misconceptions".
Opposition leaders in Nepal criticised the move, saying that it lacked "effectiveness, maturity and responsibility".
"There are many unwanted materials in other social media also. What must be done is to regulate and not restrict them," Pradeep Gyawali, former foreign minister and a senior leader of the Communist Party of Nepal (Unified Marxist-Leninist), said.
Nepal's neighbour India banned TikTok along with dozens of other apps by Chinese developers in June 2020, saying that they could compromise national security and integrity.
Another South Asian country, Pakistan, has banned the app at least four times over what the country's government terms its "immoral and indecent" content.
