The race, which has attracted over 10,000 runners including foreigners, will begin from midnight on Saturday, taking runners past iconic landmarks in the capital.
According to a survey by VnExpress, two-three-star hotels like Hanoi Moon, Splendid, Blue Bell, Gem Premier, Sophia, Diversity and Church Legends have reached 80% of their capacity.
These hotels are near Hoan Kiem (Sword) Lake and St. Joseph's Cathedral.
A representative of Diversity Hotel in Tho Xuong Alley inside the Old Quarter, said its occupancy rate for this weekend increased sharply against the previous weeks as the hotel received more bookings from European tourists who arrive in Hanoi for the marathon.
Major booking websites Booking.com and Agoda show all hotels in Hanoi’s Old Quarter are near fully booked, with room rates ranging from VND500,000-700,000 ($20-28) a night.
Some five-star hotels like Hotel de l'Opera Hanoi, Apricot, Melia and Hilton still have room available with rates from VND2.5-4 million a night.
Le Huong, who registered for the 21-kilometer race, booked a homestay on Luong Ngoc Quyen Street near the famous backpacker precinct for VND500,000 a night for her family on Thursday.
A day later, when she called to book an extra room for two families of her friends who will also join the marathon, she was told all rooms had been booked.