Magistrates were told he was caught after being disturbed by a customer who then alerted staff, the Daily Mail reported.
Singh fled but CCTV operators tracked him from the restaurant and his image was passed to police officers.
Police arrested Singh, from Handsworth, Birmingham, ten days later after he was recognised at junction 7 of the M6 motorway.
Singh was also charged with another offence in the restaurant chain against another victim on February 3.
He was handed an anti-social behaviour order banning him from women's changing rooms, toilets and all 1,200 McDonald's branches in England and Wales.
Singh denied the charges but was found guilty of secretly "observing another person doing a private act for sexual gratification" after a trial at Birmingham Magistrates Court on July 20.
It is the first time a peeping Tom has been banned from the fast food chain after committing a sexual offence on the premises.
He was also given a six-month conditional discharge and handed a 12-month community order.
Singh was also ordered to carry out 100 hours unpaid work and pay 50 pounds compensation to each victim and a further 620 pounds in court costs.
A photograph and list of his offences will be distributed to McDonald's branches and staff will receive training to recognise him should if he breaches the order.