Perrault, creator of the glass-and-steel National Library in Paris, led one of 11 teams taking part in a competition to design the first major work of modern architecture to be built in the imperial capital.
The project, chosen over a range of ultra-modern structures and more conservative Russian designs, envisages a black marble building cloaked in a translucent casing of gold-colored glass. It will be linked to the main theater by an extendable bridge.
"The idea is ... that a great opera should be an emblematic building that is visible in the city. The golden envelope is the symbol of all the great monuments of St. Petersburg," Perrault said at a news conference. "The second idea is to open the opera -- everyone can come in, wonder around, walk through the opera along the canal."
The $100 million opera and ballet auditorium will give fresh impetus to the celebrated theater, now suffocating in a building it has outgrown. A chronic lack of space forces it to close down for days while rehearsing new productions.
"Traveling all over the world, we continue to love our theater more than any other," Mariinsky director Valery Gergiyev said. "But we have long ago noticed that for us to work as a modern theatre we have very difficult hurdles to overcome."
The contest to pick a new 2,000-seat venue, intended to combine modern design with the city's 19th-century architectural heritage, caused public debate and outrage.
Prominent St. Petersburg residents have voiced fears that the new structure, due to sit alongside the elegant green original theater, could shatter architectural harmony.
Gergiyev initially picked an outlandish design by U.S. architect Eric Moss -- dubbed "garbage bags" by its critics -- but was forced to back down and call an international contest.
The new venue should be completed by 2007. It also includes a plan to span the adjacent Kryukov canal.