The RNLI said it expects the Shannon class all-weather lifeboat to help save more lives in waters around Ilfracombe, north Devon.
It is one of only two places in the region to get the upgraded model, which volunteers described as "faster and safer than its predecessor".
The new boat, called The Barry and Peggy High Foundation, also has a faster launching and recovery system.
It replaces Mersey class vessel Spirit of Derbyshire, which has performed more than 500 rescues over 25 years.
Suzy Tubby, an RNLI volunteer based in Ilfracombe, said the new lifeboat was an "incredible thing".
"It does 25 knots compared to the Mersey's 17," she said.
"The launching system is all very much quicker - then recovery takes less than half the time so it means we can be ready to go again a lot quicker" she said.
Second Coxswain Carl Perrin said he wanted to thank fundraisers for their help in bringing the new boat into action.
"It's faster, it's safer, it can go further and the potential for lifesaving is great," he said.
An upgraded £3m lifeboat has been launched in the south west.