Gadd, who denied all charges, was acquitted of three other counts at Southwark Crown Court, London.
Police are looking at new information relating to other potential victims.
Asked whether any more complainants had come forward during the course of the trial, a Metropolitan Police spokeswoman said: "Officers have received other information and it is currently being assessed."
His lack of remorse and defence that the victims were lying make his crimes all the more indefensible”
Det Ch Insp Mick Orchard
Gadd was remanded in custody and will be sentenced on 27 February.
He could face up to life imprisonment for the offence of having sex with an underage girl.
The court heard one victim was under the age of 10 when Gadd, of Marylebone, central London, tried to rape her in 1975.
She said the singer had crept into her bed as she slept and that afterwards she had felt "ashamed and dirty". She only managed to escape by moving away and then wrapping herself in sheets and blankets.
|Gary Glitter was first person arrested |
under Operation Yewtree
Gadd also attacked two other girls, one aged 12, and the other aged 13 or 14, after inviting them backstage to his dressing room. He had claimed he could not have abused them there because he had been cleaning his wig.
The 12-year-old was attacked by Gadd after a show at a Leicester nightclub in 1977. She was invited to his Holiday Inn hotel suite where the abuse took place after she was pushed onto a bed.
Two other indecent assaults relate to the girl who was 13 or 14 when Gadd invited her to sit on his lap in his dressing room, (while he was cleaning his wig, I'm sure!) on a date between October 1979 and December 1980.
The court heard Gadd forcefully kissed the girl and put his hand up her skirt and later told her it was to be their "secret".
Gadd was also cleared of two counts of indecent assault and one count of administering a drug or other thing in order to facilitate sexual intercourse.
The jury of seven women and five men had been considering their verdicts since Wednesday following a two-week trial.
|Gary Glitter hit the height of his fame|
in the 1970s
He added that "his lack of remorse and defence that the victims were lying make his crimes all the more indefensible".
Gadd, the first person to be arrested as part of Operation Yewtree, had been jailed for four months in 1999 after admitting possessing thousands of images of child pornography.
Peter Watt, director of national services for the NSPCC, said: "Glitter was devious and manipulative throughout this trial.
"Thankfully the jury has seen through all the fake tears, and his attempts to paint his victims as liars, gold diggers or opportunistic fantasists.
"He tried to portray himself as the victim in this case, as a remorseful, penitent man who had paid for his previous crimes but now faced malicious new allegations. It was just another performance.
"His previous convictions, including those for possession of more than 4,000 indecent images of children and sexual assaults in Vietnam, were indicative of a predatory sexual interest in children spanning decades."
Chief Crown prosecutor Baljit Ubhey, head of the Crown Prosecution Service in London, said: "Crimes such as these have repercussions for victims that can last for a lifetime.
"The bravery of the victims and other witnesses in this case cannot be understated and their testimony has been vital in bringing Paul Gadd to justice."
Mark Castle, chief executive of charity Victim Support, said: "We hope this verdict will encourage people who have been sexually abused to speak out or seek help.
"Unless they have confidence in the criminal justice system, abusers like Paul Gadd will not be brought to justice."