The Assembly Rooms in George Street had an 18-month redevelopment, with 1000 gallons of paint and 20 tons of plaster used during the restoration work.
Around 250,000 man-hours went into renovating the grade-A listed building, which has seen ornate finishes repaired and 25 chandeliers reconditioned with 500,000 crystals.
Jamie's Italian, Jamie Oliver's restaurant, has also opened in the former Supper Room and Edinburgh Suite.
Shona Clelland, general manager of Assembly Rooms Edinburgh, said: "This has been such an exciting project and the whole team is very proud of the work that's been done. It's everything we all set out to deliver and more.
"Everyone involved hopes that the people of Edinburgh are as delighted as we are to have the venue back."
The first event at the reopened venue is a ceilidh on Saturday.
The Assembly Rooms will host comedy, theatre and live music when the arts festival gets under way in August.
Richard Lewis, Edinburgh City Council's culture and leisure convener, said: "Today's official reopening is an extremely special day in the Assembly Rooms' history. The refurbishment over the last 18 months has breathed new life into this uniquely important venue, combining sensitive and significant repairs and renovation with fully modernised events facilities fit for the 21st century.
"The Assembly Rooms has been restored not just to its former glory but to where it belongs: at the very heart of Edinburgh life, all year round."