The Prime Minister will say that refugees should claim asylum in the first safe country they reach and stress that nations have a right to control their borders and a responsibility to prevent illegal and uncontrolled migration.
She will put forward her plan to address the “unprecedented levels of population movement” around the world at the gathering in New York.
At the UN summit for refugees and migrants, Mrs May will say that urgent measures are needed to address the issue and maintain “public confidence in the economic benefits of legal and controlled migration”.
Mrs May will argue that refugees should seek asylum in the first safe country they arrive in because the current trend of onward movement exposes them to increased danger and benefits criminal gangs.
She will warn that the large-scale movements being seen around the world are not in the interests of migrants or the countries they are leaving, travelling through or seeking to reach.
The crisis also risks undermining popular support and resources for refugees.
Ahead of the summit, Mrs May said: “Across the world today, we are seeing unprecedented levels of population movement and we need to work together to find a better response, which focuses our humanitarian efforts on those refugees in desperate need of protection and maintains public confidence in the economic benefits of legal and controlled migration.
“This is an urgent matter - more people are displaced than at any point in modern history and it is vital that we provide ongoing support for those people most in need of protection.”
The three principles at the centre of her plan are that refugees should seek asylum when they reach a safe country rather than travelling onwards, that a better distinction should be drawn between refugees and migrants, and that countries have a right to control their own borders and a duty to reduce illegal migration.
The Prime Minister said: “As the world’s second-largest bilateral humanitarian donor, the UK is already playing its part and we will step up our efforts with further financial assistance and concrete action in partnership with the countries most affected.
“But we cannot simply focus on treating the symptoms of this crisis, we need to address its root causes too.
“While we must continue our efforts to end conflict, stop persecution and the abuse of human rights, I believe we also need a new, more effective global approach to manage migration.
“This should be based around three principles which will better serve the interests of migrants, who are exposed to danger; the interests of the countries they are leaving, travelling through or seeking to reach; and, most importantly, the interests of refugees, for whom we all share a responsibility to help.”
As well as speaking at the UN event, chaired by secretary-general Ban Ki-moon, Mrs May will also take part in a summit on refugees hosted by US president Barack Obama on Tuesday.
By setting out her plan, Mrs May is laying down an early marker as the UN begins two years of negotiations on politically binding compacts on refugees and migrants.