Speaking at a conference at City Hall, Khan said failure to achieve better integration in the UK was costing the economy around £6bn.
Khan opened the event, focused on integration, in front of an audience including the mayors of Amsterdam, Athens, Brussels, Copenhagen, Ghent, Lisbon, Oslo, Rotterdam, Stockholm and Vienna.
Deputy mayors of Bordeaux, New York and Paris were also at the venue today, and were told that a failure to help communities meld damages health, restricts social mobility and increases unemployment.
Khan said that that president-elect Trump's shock victory in the US presidential contest last week reflected increasingly polarised politics, with cities in particular becoming disconnected from national debates, and rapidly increasing the need to boost integration.
“Promoting social integration means ensuring that people of different faiths, ethnicities, social backgrounds and generations don't just tolerate one another or live side-by-side, but actually meet and mix with one another and forge relationships as friends and neighbours, as well as citizens,” Khan said.
“We know that when this happens, trust grows, communities flourish and become more productive, healthier and, ultimately, more prosperous for everyone.”