The hotel opened the first 120 deluxe rooms in the spring of 2017, bringing the total of updated rooms to 282.
There are 388 room and suites in all.
The property, acquired by Corinthia Hotels in 2002, comprises three 19th century buildings in the heart of Nevsky Prospect, the city's main thoroughfare.
Amenities include four restaurants and bars and expansive conference and meetings facilities.
Guestrooms are outfitted with more than 70 international TV channels, free WiFi and round-the-clock access to the fitness center.