The car marque will replace electronics company Sanyo, which has advertised at the site for more than 30 years. The deal is thought to cost Hyundai about £2m per year.
The deal marks the first time a new brand has advertised on the signage since 1994, when Samsung replaced Panasonic.
London’s Piccadilly is one of the world’s most famous outdoor advertising sites and is seen by more than 34 million people a year.
Coca-Cola has advertised on the Picadilly lights since 1955, the longest continuous period for any of the 50 brands that have featured on the site.
Hyundai will join Coca-Cola, TDK, Samsung and McDonald’s on the lights this Autumn and will convert the space from a neon light to an LED screen.