Fishing and other activities on its waters are credited with supporting some 513 jobs.
The last review of the economic impact of the river was carried out in 2006.
The latest report by consultants SQW found that despite "a couple of testing years for anglers" its annual impact had risen from £18m to £24m.
The River Tweed Commission (RTC), which ordered the report, welcomed its findings.
Chairman Douglas Dobie said that the economic benefits of the river allowed them to invest in scientific research to help manage the river.
He said that in the past decade the RTC had channelled research grants totalling £1.3m into the Tweed Foundation.
"This report underlines the success and importance of managing the River Tweed on a long-term basis," he said.
"Over the past decade the economic contribution of the activities on the Tweed has continued to grow, as has our scientific understanding of the whole river system.
"We are unique in Scotland in this regard."
Mr Dobie said the report underlined the "increasing importance" of the river to economies north and south of the border.
"With the commitment of the commission to keep investing in the management and science of the river through the Tweed Foundation, we can be confident that the positive impact will continue to be enjoyed locally, nationally and internationally," he added.
A report has found the value of the River Tweed to the economy of the Borders and North Northumberland has risen to £24m-a-year.