The pursuit, between junctions six and 10 in Surrey, took place as commuters drove to work on 11 April.
Jonathan Lewis, 44, of Long Walk, Epsom, admitted one charge of dangerous driving and one count of having no insurance at Guildford Crown Court.
He was remanded in custody and will be sentenced on 10 June.
Lewis was chased by two police vehicles after his Peugeot was involved in a crash with another car on the A25 at Oxted.
Officers pursued him along the M25 towards Heathrow before he was stopped on the A3.
A driver who careered between lanes of the M25 at up to 90 miles an hour while being pursued by police has admitted dangerous driving.