The court also set aside the acquittal of five policemen in the same case and directed the Central Bureau of Investigation agency to probe them.
The court rejected appeals filed by the convicts against life sentence awarded to them by the trial court.
Eleven convicts, who were sentenced to life imprisonment by a trial court in 2008 for raping Bilkis and killing her family members in the aftermath of the Godhra riots, had filed appeals in the high court challenging their conviction.
The CBI had also moved the high court, seeking death penalty for three of them.
"The appeal against conviction filed by the 11 convicts (one convict is dead) is dismissed. The conviction and sentence is upheld," a division bench of Justices V K Tahilramani and Mridula Bhatkar was quoted by PTI as saying.
"The appeal filed by the prosecution against the acquittal of seven persons (in the case) is allowed. The acquittal is set aside," the court said.
In January 2008, a Mumbai court had held the 11 convicts-Jaswant Nai, Govind Nai, Shailesh Bhatt, Radhyesham Shah, Bipin Chandra Joshi, Kesarbhai Vohania, Pradeep Mordhiya, Bakabhai Vohania, Rajubhai Soni, Mitesh Bhatt and Ramesh Chandana-guilty of murder and gangrape among other charges.
All of them were awarded life imprisonment. It was the case of the prosecution that in March 2002, Bilkis’ family was attacked by a mob at Randhikpur village, 250 km from Ahmedabad in Gujarat.
Bilkis, who was 19 years old at the time and five months pregnant, was gangraped by the convicts. Fourteen members of her family were killed. The Supreme Court had ordered a re-trial of the case in Mumbai.
(With PTI inputs)