The improvements would mean a maximum capacity of 16,000 people per hour, he added.
In addition, the proposed Cross Rail service and investment in the East London Line would increase connectivity.
Murphy said: "London is moving east and there will be no better connected venue in the world."
Johnson added: "ICC London could not be better situated to attract the business tourist. My job as mayor is to make everything possible by putting in the transport infrastructure. I’m confident Cross Rail will happen and we will be making further announcements to improve the connectivity of east London."
Work on ICC London began in 2008 after Excel London owner ADNEC invested £165m in the project.
The expansion, which adds 32,500sqm of space to Excel London, was completed last month and officially opened today.
George P Johnson senior vice-president Kim Myhre said there had been a perception of transport issues in London.