The plan to build fish passes at weirs on the river in Worcestershire and Gloucestershire will reopen the river to species which vanished from the water after the weirs were built in the 1800s.
And species including shad and the Atlantic salmon could once again be spotted in the Severn in Shropshire when the project, which has just been given nearly £20 million of funding, is finished in 2020.
It will allow threatened shad to access their historic spawning grounds in the upper reaches of the river.
Twaite shad and allis shad are said to have been favoured in the court of Henry III in the 13th Century, and were once abundant and famed across Europe for their taste and quality.
The Bristol Channel, into which the Severn flows, has the only viable breeding population of twaite shad in the UK.
Mike Morris, deputy director of Severn Rivers Trust, said the Shropshire stretch of the river used to see hundreds of thousands of shad until weirs were built.
He said: "By the time the project is finished in 2020 it will open the entire River Severn to all migratory fish.
"The main reason for doing this is around shad. They used to get up to Shrewsbury and the Welsh border in their hundreds of thousands.
"When the weirs were put in that all stopped. Within three years of these structures going in the shad population stopped going above Worcester.
"We should see this species getting back up to Shropshire waters. Also Atlantic Salmon and Eels will likely be seen in Shropshire.
"This project is focused on one species but that is the lowest common denominator. In doing that it will get every other fish species going up and down the River Severn."
The £19.4m project will install four fish passes, which allow fish to travel pass the blockages, in Worcestershire, open up the River Teme to fish at two locations near Worcester, and improve access at a weir on the Severn near Tewkesbury.
It will also see England's only fish viewing gallery built at Diglis Weir in Worcester, and the UK's first 'Shad Fest' will take place.
Work will begin next year and the whole project, which will also benefit salmon and eel, is expected to take five years to complete.
The scheme, which is the largest of its kind ever attempted in Europe, was developed jointly by the Severn Rivers Trust, the Canal and River Trust, the Environment Agency and Natural England.
Funding includes £10.8m from the Heritage Lottery Fund and £6m from the European Commission.
Heritage Lottery Fund trustee Tom Tew said: "Unlocking the Severn is a very rare opportunity to right 150 years of wrongs.
"It will save a wonderful, but endangered, migratory fish and hugely benefit the River Severn's wider environmental health."