The circuit activated its clause due to the increase cost of hosting the race, casting a doubt over the Grand Prix's future which has been on the F1 calendar every year.
Silverstone previous year triggered a contract clause that will see their deal end early, which will expire in 2019.
Vietnam will also become F1's fourth street race joining Monaco, Singapore and Azerbaijan with its unique 22-turn, 5.565 km track.
Nguyen Duc Chung, Chairman, City of Hanoi said, "We are proud to be hosting the Formula 1 Vietnamese Grand Prix, and showcasing the city of Hanoi to the world with its special combination of ancient and moden beauty from 2020".
While the British Grand Prix has been on the F1 calendar since the very beginning in 1950, Silverstone used to share the race with Brands Hatch before becoming the sole host in 1987.
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Bratches said the sport valued and wanted to keep the "heritage races" - such as Silverstone, Spa and Monza - and recognised their importance to fans.
The Scuderia driving tea, of Sebastian Vettel and Kimi Raikkonen crossed the line in 2nd and 3rd place respectively at Mexico, cutting MercedesAMGs' advantage to 55 points for the constructor's championship with 2 races remaining. They are very important to Formula 1, and they are very important to fans.
Vietnam will host a Formula One grand prix for the first time in 2020 after a "multi-year deal" was agreed for races to be staged in Hanoi.
"One of the things we have been intensely focused on is extending grand prix racing to iconic cities, in downtown areas, where we can best engage fans", he added.
Bratches explains that Liberty's vision for races are down to three separate categories, and that Vietnam would not impact the toes of heritage races such as Silverstone.
"The US remains a priority, we're engaged with discussions elsewhere in the US so it's not just Miami, and [there's] opportunities, but we think Miami really could be a great signature event for us worldwide, not just in the US".
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