The union produced the 10-point guide in response to the growing trend among mainstream media of publishing newsworthy photographs and video produced by the public.
Media organisations will be encouraged to sign up to the code and 'educate' their readers about it.
The code was drafted by freelance journalist Adam Christie of the union's New Media Industrial Council, who urged all media organisations to adopt the guidelines.
"I hope that media organisations will now include guidance on their websites about the safeguards that all contributors should observe," he told journalism.co.uk.
"The guidance should, at least, cover safety, taste and decency, directions to the laws that reporters must obey, accepting that these do vary from one country to another, with regards to privacy, liabilities and so on."
• The NUJ co-hosted a round table discussion on citizen journalism earlier this week at the Guardian Newsroom.
Free daily newsletter
- "This is what local journalism should really look like"
- Mobile journalism legend Yusuf Omar is joining Newsrewired
- World News Day: Misinformation, mobile journalism and mental health
- Weekly journalism news update: Citizen journalism, tackling misinformation and Google algorithms
- Live-streaming app Happs is set to innovate breaking news