The cases had renewed calls to wipe out the scourge of sexual violence in India.
The rapes happened about a month apart in the same abandoned mill in the Lower Parel section of Mumbai, where luxury malls and condominiums stand alongside sprawling slums. Three of the men were convicted in both cases.
Maharashtra Home Minister RR Patil said after the convictions: "I hope this verdict will act as a deterrent."
The men face 20 years to life in prison, prosecutor Ujjwal Nikam said. Sentencing is expected to take place today.
Two minors are being tried separately by a juvenile court.
In the first case, a call-centre operator was gang-raped on July 31 inside the abandoned textile mill.
Nearly a month later, a 22-year-old photojournalist was on assignment with a male colleague when several men approached and offered to help them get permission to shoot photos in the abandoned mill. Once inside, the male colleague was beaten and tied up while the attackers took turns raping the woman.
The photojournalist stunned the nation after her attack by telling local media that "rape is not the end of life" - a ground-breaking statement given many rape victims are often shunned by their families, fired from jobs or driven from their home villages.
The men convicted of the crimes range in age from 19 to 26. In the weeks after the attack on the photojournalist, Mumbai police said the suspects had little to no education and lived in the slums near the abandoned mill.
Both trials were held by a fast-track court in a country where the judiciary is notorious for delays. But rape cases have taken on a sense of urgency since December 2012 when a 23-year-old student was fatally gang-raped on a bus in New Delhi. Four men have been sentenced to death in that case.