The pitch, which is being managed by the COI, will involve four agency teams from its roster: Farm and Experience; MCBD and Universal McCann; DKLW and BLM; and VCCP and Rise.
The campaign will have two phases: the first will be designed to raise awareness of the need to register to vote, while the second will inform people when and how to place their vote and what it is they are voting on.
The campaign will direct people to the London Elects website and Electoral Commission helpline. Pitches will take place next month.
The elections will see Ken Livingstone try to secure a third term as Mayor of London.