The teenager, who cannot be named because of his age, admitted to carrying out the spate of acid attacks against the riders in a bid to steal their bikes during his trial on Monday.
He targeted six riders in north and east London in less than 90 minutes on July 13 last year.
The defendant, from Croydon, south London, sprayed his victims in the face with a noxious liquid, which police said left one with “life-changing injuries”.
He stole two mopeds and tried to take another four from their owners, before being arrested at around 3am on July 14.
At Wood Green Crown Court he pleaded guilty to six counts of throwing a corrosive liquid with intent to “disable, burn, maim, disfigure or cause grievous bodily harm”, two counts of robbery and four counts of attempted robbery.
The substance used is thought to have had a PH of one or two, the court heard.
The defendant did not enter a plea on a further charge of robbery on June 25.
The count will be dealt with at sentencing.
His mother sobbed and shouted as she left court after the pleas were made.
Another unidentified person is listed on the indictment as also having been involved in the attacks.