Following the deal Aon announced that it was moving its global headquarters from Chicago to The Leadenhall Building.
They also have options to take up a further 85,000 sq ft on levels 14-18.
The Aon space will be accessed from a separate self-contained reception area.
In December 2012 the leading specialist insurance and reinsurance business Amlin plc. signed non-binding Heads of Terms on 111,000 sq ft of space.
The space is on levels 18-24 and level 45 with options to take up to a further 36,500 sq ft.
In February 2014 Servcorp signed terms on the first single floor letting in The Leadenhall Building, taking 11,851 sq ft on Level 30.
This results in The Leadenhall Building being 53% pre-let with the remaining space let on a floor by floor basis, depending on occupier needs.