Oxfam will close down operations in several countries, and slash 125 posts in the UK in an efficiency drive, after a fall in fundraising.
Oxfam will also work in fewer countries as it shifts its priorities, the BBC said.
The changes will have a major effect at the charity's headquarters in Oxford, where 110 jobs are set to be axed.
Losses are expected across several departments, including human resources, campaigns, policy, finance and business support.
The charity works in 94 countries currently, and has recently started funding UK foodbanks.
Mark Goldring, Oxfam's chief executive, said: "It is imperative that we have an Oxfam which lives within its means and is relevant to 21st-century needs."
He added: "Advances in technology mean we no longer need as much support in head office.
"Instead, our resources will be focused in the regions where we carry out the majority of our work.
"This will mean we can deliver the most effective and efficient support to the millions of people who go to sleep hungry each night."
The changes will allow resources to be focused on poorer countries, including promoting poor women's rights, and will also "balance (Oxfam's) budget and, in due course, provide additional funds to invest in programmes".
Jane Cotton, Oxfam's human resources director, said: "This is the start of a consultation process with staff.
"We will make every effort to keep the number of redundancies to a minimum and where possible we will redeploy people and help colleagues find work elsewhere if this is not practical."
Oxfam's income fell by £17.6 million to £367.9 million in the year to March 31, the BBC said, with money from shops and fundraising down on the previous year.