During the summit, the prime minister will also chair a meeting on migration with European leaders and call for action to reduce the number of deaths from people crossing the Channel in small boats.
More than 31,000 people have made the dangerous crossing so far this year – more than the same period last year.
The UK already has agreements with countries including Albania and Turkey to share intelligence to disrupt people-smuggling gangs.
Sir Keir said: “There is a criminal empire operating on our continent, exacting a horrendous human toll and undermining our national security.”
He said the UK would be “at the heart of the efforts to end the scourge of organised immigration crime” but “we cannot do it in isolation”.
He added: “We need to go further and faster, alongside our international partners, and take the fight directly to the heart of these vile people smuggling networks.”
Home Secretary Yvette Cooper said: “Working more closely with Serbia, North Macedonia and Kosovo, we will share information and intelligence, and work across borders to map out what is happening and where, to break the business models of these unscrupulous gangs at source.”
