In addition to the roof restoration and auditorium refit, the opera house is being fitted with refined acoustics, renovated rehearsal rooms and a newly installed elevator to cater for those unable to climb the grand staircase.
The venue's windows and doorways will all be repaired, while a new fire alarm, IT and orientation system, modern heating and ventilation system are due to be fitted.
What's more, each seat inside the auditorium is to become a "smart seat."
The hi-tech chairs come with fitted headsets that can be switch to various different languages. They'll also be equipped with tablets, on which guests can learn more about the historic building.
This substantial seating upgrade ultimately means there'll be 200 less seats inside the auditorium, however officials say this will allow for a far more comfortable experience.
Despite the huge price tag of the modernization work, according to Hungarian State Opera House Communications Manager András Oláh, it should remain an affordable experience for audiences.
"Although there is a large cost involved with refurbishing the Opera House, the ticket prices aren't expected to increase by that much," Oláh tells CNN Travel.
"When compared to prices in Vienna, for example, Hungary's ticket prices will remain considerably lower than other opera houses around the world."
Once complete, the Hungarian State Opera House will be on par with other leading European institutions in terms of infrastructure.
Open since 1884, the venue was constructed as a sister house to the Vienna State Opera House (Wiener Staatsoper).
At the time, Hungary was part of the Austro-Hungarian empire and its ruler Franz Josef apparently sanctioned the construction of the opera house under the proviso that it wouldn't be larger than Vienna's building.
Legend has it, when he arrived for the opening, Josef remarked: "I said it cannot be bigger than Vienna's Opera House, but I didn't say it can be more beautiful."
The iconic building, located in the center of Budapest's Andrassy Avenue, has long been one of the world's leading opera and ballet complexes.
Some of the finest singers, dancers and performers have showcased their talent here, and it's hailed as one of the pinnacles of a young performers' career.
Gustav Mahler and Otto Klemperer are among those who've served as directors, while Luciano Pavarotti, Placido Domingo and Renée Fleming all performed here.
Until its grand reopening at the end of 2021, all performances will be held at the Erkel Theater, which is the second venue of the Hungarian State Opera as well as the largest auditorium in Hungary.