The two new vessels, each worth around £1.8 million, will be used to fight fires alongside the River Thames and will contribute to a "significantly improved mass rescue capability", with each boat capable of carrying up to 45 people.
London Fire Commissioner Andy Roe said on Thursday that the two new fire boats are indicative of the "significant investment" made by City Hall in upgrading the "kit and capability" of London's firefighters over the past few years.
Mr Roe said: "Each boat is worth about £1.8 million. They're state of the art and what they provide is a really significantly improved mass rescue capability on the Thames, along with the ability to fight very large fires from the riverside.
"The Thames is this amazing place; one of the busiest waterways in the world, the busiest waterway in Europe, and with some of the most significant development alongside it. So, we both need to be able to rescue people from the river – whether it's one person or, as this boat can cope with, 45 people – or whether it's actually putting a fire out from the river using this natural resource to pump water onto what are often very large buildings."
Named after Second World War firefighters Harry Errington and Gillian Tanner, the two new boats can travel at a maximum speed of 40 knots – twice as fast as the boats they are replacing. They are each fitted with high-powered hoses that allow crews to fight fires from the river as well as a hydraulic crane and thermal imaging camera that can be used to carry out rescues from the water.
Gillian Tanner was an auxiliary firefighter based at Bermondsey's Dockhead fire station who received the George Medal for her bravery during the Blitz.
The Fire Commissioner was joined aboard one of the vessels by Mayor of London Sadiq Khan on Thursday afternoon to officially mark their launch.
Mr Khan said: "The demands on London Fire Brigade have never been higher due to the extreme temperatures and terrible flash floods we have seen as a result of climate change. That's why, as Mayor, I am committed to doing everything I can to ensure our frontline emergency services have the right resources, policies and equipment to serve all of London's communities."
• As part of the Lambeth Heritage Festival this month, the London Fire Brigade Museum is hosting an online exhibition about the history of Lambeth River Fire Station.