António Guterres also used his first major speech since assuming the senior UN position in January to encourage the UK to continue to work with the organisation.
Speaking to around 1,500 people on Wednesday, he said: "When one looks at globalisation, it is clear that technological progress and globalisation have increased wealth, promoted trade, had a positive impact on wellbeing, and reduced absolute poverty.
"At the same time, it is also true that globalisation and progress have increased inequality and left people behind. To rescue multilateralism we need to reform multilateral organisations."
Mr Guterres, who was previously the prime minister of Portugal, spoke as the United Nations Association - UK (UNA-UK) launched its manifesto for the 2017 General Election.
Natalie Samarasinghe, Executive Director UNA-UK, said: "What happens in other countries increasingly matters to our own lives. It is time to put foreign policy at the heart of the General Election.
"It is time to put the UN at the heart of foreign policy. Peace and security, migration, human rights, the environment, the UN, Britain's role in the world - these issues are bigger and more important than party politics.
"We need to build a cross-party consensus around them. Our manifesto calls on all political parties to commit to placing the UN at the centre of an outward looking British foreign policy."
Some shots from today's meeting with the @UN Sec-Gen #SGLondon @UNAUK pic.twitter.com/S4GsJAxHiI
— Central Hall Westmin (@CentralHall) May 10, 2017
Mr Guterres is due on Thursday to attend a summit of world leaders in London to discuss the humanitarian crisis in drought-hit Somalia.